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@weirdboyjim8 ай бұрын
If you came here to comment that I popped the registers in the wrong order (thereby swapping “b” and “d” rather than preserving them) well done. I didn’t spot that until previewing the final video.
@TroySchrapel8 ай бұрын
guilty. glad you found it :D
@-lolus-8 ай бұрын
nah, i am here just to watch and be in awe. grat video
@j.r.qwertz8 ай бұрын
My sense of order took off and I was about to write it. Glad you found it.
@RoamingAdhocrat8 ай бұрын
have you considered having a formal Pinned Errata Comment under every video where you put this kind of stuff?
@GodmanchesterGoblin8 ай бұрын
Yes, that's *exactly* why I came here... 😅
@Biomancer818 ай бұрын
I would very much enjoy seeing a full SPI implementation.
@weirdboyjim8 ай бұрын
Noted, I want to do enough to get a much better transfer rate.
@Biomancer818 ай бұрын
@@weirdboyjim I honestly am enjoying all of the series' and look forward to seeing more. And thank you for the response.
@rimmersbryggeri8 ай бұрын
@@Biomancer81 Same. I don't really undestand half of what James is doing but it's still fascinating.
@nockieboy8 ай бұрын
I would love to see a full SPI implementation! I had a go at designing one a couple of years ago, using parallel to serial (and vice versa) shift registers, but never had the time to finish it. Would love to see how you implement one!
@weirdboyjim8 ай бұрын
I think it can be done in a fairly straightforward way. Handling the mode variations adds a bit of complexity.
@andrewwatts19978 ай бұрын
I would love to see a full implementation! And then hooking the cpu up to a variety of " Arduino " sensors ? distance, proximity, temp and moisture etc etc.
@weirdboyjim8 ай бұрын
Yeah, having standard protocols like SPI opens the door to lots of extra things, I don';t want to dwell on that too much as Arduino type sources cover that all pretty well.
@teknifix8 ай бұрын
Last year I had a lot of fun learning SPI using my 6502 sbc and the MAX3100 serial IC. It wasn't nearly as complicated as I thought it would be. Great video, sir!
@weirdboyjim8 ай бұрын
Thanks! Glad you enjoyed it!
@emolatur8 ай бұрын
The SPI implementation used inside the atmega328p is described pretty well in the datasheet, and I've often thought about trying to design a ttl implementation of it...
@weirdboyjim8 ай бұрын
Interesting, I might take a look at that after I'm done to see how differently they did it.
@wallyhall8 ай бұрын
ISO date format ftw! YYYY-MM-DD all the way!
@weirdboyjim8 ай бұрын
I'm not going to argue!
@TomStorey968 ай бұрын
Neat. SPI will open up a world of interesting peripherals. If you want to go even faster, implement a QSPI interface and you'll get a full byte in only two clock cycles. 🙂
@weirdboyjim8 ай бұрын
I would struggle to consume data that fast!
@martinmckee53338 ай бұрын
I like the idea of a hybrid implementation as well. I have designed SPI blocks for instantiation in FPGAs and those are simple. I have also used the RP2040s PIO blocks to implement modified SPI and the protocol is highly amenable to implementation with just a handful of simple commands, so I think the SW/HW hybrid solution would be interesting to see.
@weirdboyjim8 ай бұрын
I'd like to see how few components I could use to get a transfer rate at the cpu's clock.
@Vintaronica8 ай бұрын
You have the best sounding keyboard I have ever heard. 😮
@weirdboyjim8 ай бұрын
Lol, I think there is some indirect coupling to the mic through the desk that makes it sound louder than it is, but I do tend to punch that enter key at the end of a line!
@OscarSommerbo8 ай бұрын
A hybrid approach would probably be the most fun and rewarding. While throwing a bunch of silicon at the problem has its allure, it would reduce the flexibility that software gives, while doing it all in software will be slow and tedious. So a mixed approach is what I would favor.
@weirdboyjim8 ай бұрын
My plan is to try and expand it incrementally testing different component trade offs against the speed benefit.
@OscarSommerbo8 ай бұрын
@@weirdboyjim Sounds like the logical and sound approach I have come to expect. I'm looking forward to it!
@richardlincoln8867 ай бұрын
FWIW, you've inspired me - not just this video but the series. I always fancied Forth, wrote interpreter/compilers as a teenager on C64/6510 and then 68k on Amigas. At least on paper, I'm going to tinker with a simple Stack based CPU. Sure - its been done before, but the mental exercise of drilling down to microcode/metal level with potential for implementation on 74 series chips is irresistible - kind of like learning to code in the early 1980s. Heading back to the infinite rabbit hole of computing :) Great series - many thanks for sharing your progress.
@weirdboyjim7 ай бұрын
You are very welcome Richard! Good luck with your build, maybe join the discord and share some details?
@daskasspatzle23968 ай бұрын
Well done again :-) I would prefer to see the full hardware SPI implementation.
@weirdboyjim8 ай бұрын
Thanks! I've been giving some thought on how to approach it but I have another couple of videos to work on first.
@OriginalJetForMe8 ай бұрын
Absolutely make a full SPI hardware block!
@weirdboyjim8 ай бұрын
I'll see what I can do, I'll definitely take the circuit further!
@maffsie8 ай бұрын
Being honest, I'd like to see a full implementation of SPI if just because I want to see the process of designing and implementing a peripheral like that.
@weirdboyjim8 ай бұрын
I'll definitely extend the circuit, not sure how far I'll go with it yet.
@atomic148 ай бұрын
I've always wondered what SPI mode actually referred to. Now I know - thanks James!
@weirdboyjim8 ай бұрын
Glad you found it interesting Chris! This is one of those times I suspect a committee couldn't agree and so the variations became "modes".
@_Funtime608 ай бұрын
A partial implementation would be neat, but it'd bug me that it'd be incomplete. What I'm more interested in is the variety of SPI devices out there. IIRC SD cards do SPI but there's also SPI to Ethernet adapters. you'd still need to do a lot more to get online but the possibility is cool enough.
@weirdboyjim8 ай бұрын
An interesting discussion is "what constitutes complete". For me that would be read/'write a byte without supervision.
@_Funtime608 ай бұрын
@@weirdboyjim I certainly don't know myself.
@porklaser8 ай бұрын
A common technique I've seen in microcontrollers is to (ab)use the spi peripheral to achieve certian I/O tasks faster than they can be done on the gpio. Maybe an I/O peripheral that could be leveraged to do things like SPI and something else like I2c would be useful. Or maybe that would be scope creep. :)
@weirdboyjim8 ай бұрын
It does make a lot of sense!
@ingmarm88588 ай бұрын
Nice work, great video as usual, I'm inspired to go interface some slave devices on the bench.
@weirdboyjim8 ай бұрын
I see what you did there....
@vitormoreno12448 ай бұрын
If you have a spare peripheral line on hand you can build a 4MHz hardware SPI with 4 ICs, just use the good old 74HC165 for MOSI and 74HC595 for MISO and some basic logic ports.
@weirdboyjim8 ай бұрын
4 IC's? I can see a full speed hybrid with less than that but I've not planned out a full implementation yet.
@alexloktionoff68338 ай бұрын
Is it possible cost/performance efficient implementation? i.e. add one chip, but increase order of magnitude performance? @@weirdboyjim
@JonnyBergdahl8 ай бұрын
I would love to see a hardware implementation!
@weirdboyjim8 ай бұрын
How much of that is because it would give me enough bandwidth to stream Rick Astley?
@JonnyBergdahl8 ай бұрын
@@weirdboyjim I would say about 50%. And a hybrid solution would be interesting.
@nahkamursu8 ай бұрын
i love artificial limits like making sure chip count stays low :)
@weirdboyjim8 ай бұрын
So do I although once you factor cost or space into the equation those limits may not be artificial!
@fredflintstone9048 ай бұрын
In the software version a single routine which does a swap will work for either a read or a write. That would take a few more cycles when just a reading or writing but would save some code. (When reading it doesn't matter what ends up going out on MOSI.) I always enjoy the puzzle of doing a minimal hardware acceleration of some software.
@weirdboyjim8 ай бұрын
Indeed, but the logic flow of what I did here made more sense for the video. I like to build things up incrementaly.
@hamdanmahmood346Ай бұрын
Awesome video - thank you!
@weirdboyjimАй бұрын
Thanks! Glad you found it interesting!
@helmutzollner54967 ай бұрын
Hi James! Great Flic! Yes, go for a minimal chip and max speed approach in hardware. Curious to see how you can implement thatbwithpit Interrupts.
@weirdboyjim7 ай бұрын
I'm leaning in that direction. Partially because of how much ambiguity there is in "Full implementation".
@colinstu8 ай бұрын
17:37 ISO-8601 FTW!!!
@weirdboyjim8 ай бұрын
Definitely for date!
@FrankGevaerts8 ай бұрын
I wish what you said about date order wasn't controversial... I fully agree, today is either 14/12/2023 or 2023-12-14 (I'm used to dashes for the "correct" order). Any other order is just weird and illogical! (the rest of the video is also interesting :) ) I think some simple hardware help would be interesting and useful. Having things go faster than pure software bitbanging should expand the possibilities a lot and change the way you use things. I think even for the RTC, I suspect if you wanted to show a timer on screen now (say a game level elapsed time thing) you'd use some sort of VGA frame counter or something like that and you wouldn't waste hundreds of cycles to read the RTC just for that, but if that gets reduced to say a dozen or two cycles the option will be there.
@weirdboyjim8 ай бұрын
Thanks! If your code is synced to vga frames then a frame counter is trivial but it can be nice to have a time source you don't need to monitor.
@RoamingAdhocrat8 ай бұрын
yyyy-mm-dd (with leading zeros) is the international standard, ISO8601. I always use either ISO8601 or if I'm localising for Britishers, I'll spell out the month, e.g. 07 Dec 2023, so there's no chance of confusion with 2023-07-12
@AJB2K38 ай бұрын
Yeh, month, day ,year or year, day, month is just wrong
@BillySugger19658 ай бұрын
IEC 8601 every day 😂
@bzuidgeest8 ай бұрын
Month first is something the Americans got from the British. And it certainly isn't the most used format. That is either day first or year first as in the iso standard. But you cannot blame the guy for being born British.
@Zer0ji8 ай бұрын
Regarding sensibly sorted date formats: ISO 8601 takes care of this, and uses - as a separator Current time: 2023-12-29T17:50+01:00
@weirdboyjim8 ай бұрын
If only we didn't have to worry a about time zones!
@theboot1008 ай бұрын
James your amazing! Software SPI protocal in half a day in assembly 😮 I would love to see you build a full hardware SPI set up and see what speeds you could get. Would you create a buffer for in/out?
@weirdboyjim8 ай бұрын
Thanks! Very kind words! I'm not sure a buffer would be a benefit here. All the devices I've looked at could max out the transfer speed I can hope for but most importantly do so on demand. There wouldn't be any benefit above my reading it directly.
@WayneMetcalf8 ай бұрын
And where were you when I was fumbling around trying to learn SPI? 😅😂 Awesome vid as always. 😊
@weirdboyjim8 ай бұрын
Glad you found it interesting!
@TrollingAround8 ай бұрын
Thoroughly enjoyed this, thanks 🙂
@weirdboyjim8 ай бұрын
Glad you enjoyed it!
@LeeSmith-cf1vo8 ай бұрын
I think it would be interesting to have the unrolled loop in hardware. This may have little/no effect on the overall transfer speed (assuming the spi is using the same clock) but might free up the cpu to do something else while it waits for an entire byte to be available. Not a very efficient way to do things here, but a good opportunity to demonstrate async i/o maybe?
@weirdboyjim8 ай бұрын
I was thinking, Just the addition of single shift register to pull the bits in and let you read all 8 at once would double the read speed.
@sebastiendumais42468 ай бұрын
Hi! I have watched most of the videos on your channel and I really enjoyed the progression! It’s actually inspired me to start my own homebrew “modern retro computer”…. One thing that I didn’t see and I was curious about is how big is the full build at this point…. It seems like the size of about “3 hands wide😅” but I’m curious to see how big it actually is…
@weirdboyjim8 ай бұрын
Well, the new laminated board it's all sat on is 90x45cm. The Cpu itself is 38.5x31 so what you see in this video is about 67cm wide. The final build once everything is concerted to pcb and mounted should be about the same.
@Schwuuuuup8 ай бұрын
Most interesting application for high speed SPI for me is graphics. I would love to see the machine to show animated video on an off the shelf spi tft display. If this would work with your simple approach, I would cheer for it. But if the simple approach cannot deliver the needed SPI mode or if varying bit widths are needed (some sensors have 12 or 14bit spi, if I recall correctly) I would like to see the full blown version. In other words if the SPI is just a proof of concept it's no good, but it does not have to support every mode that theoretically exist but no device really relies on
@weirdboyjim8 ай бұрын
Comments seem to be dragging me towards a full blown version. Problem with doing graphics over spi is the bandwidth would never come close to the vga sub system sat directly on the main bus!
@akkudakkupl8 ай бұрын
He already is hurting for raw bus speed to do full resolution VGA with the dedicated hardware, SPI display has way more overhead than that and yet lower bus speed - might be OK for static images or some very low fps stuff.
@Schwuuuuup8 ай бұрын
@@weirdboyjim no, sorry, I didn't mean a replacement for the "GPU" I was thinking about a status display or touch screen interface with some blinkenlights. Not youtube on the screen
@penguineer7 ай бұрын
I would be very interested in seeing a full SPI hardware build. Did a reduced version recently for an 80s style electronics clock. :)
@weirdboyjim7 ай бұрын
I definitely want to get the transfer rate up!
@GorgotMM8 ай бұрын
I would love to see a full SPI implementation, maybe interfacing more RAM, a flash device, things like that.
@weirdboyjim8 ай бұрын
I don't think this is the right way to go for ram, but it does give us some storage options!
@vaclav_mach8 ай бұрын
I’m curious about the DS1391 time accuracy because of its’ external crystal. I used DS1307 (ext crystal, I2C) for my watch project and it drifted like half an hour per month. After switching to DS3231 with integrated crystal and temperature correction it now drifts just few seconds per month. Maybe it would be worth it to switch to SPI based DS3234? Maybe it’s overkill though, but I can imagine in some more permanent exhibitions/installations it would make sense 🙂 and it also has an 256 byte battery backed SRAM, could be used for some experiments.
@weirdboyjim8 ай бұрын
Interesting, I just powered it back up. It's about 1:15 in advance of my pc clock, but it wasn't set perfectly to the second. That's about 23 days since I set it. I'll run some more structured tests when I get an opportunity.
@vaclav_mach8 ай бұрын
@@weirdboyjim 1:15 is quite a good result, thanks! It makes sense, since it’s probably in a relatively stable conditions… compared to having it mounted all day on a wrist when it’s 30 degrees C outside (40 in direct sunlight) and 20 deg C inside.
@mekafinchi8 ай бұрын
Funny to see your homebrew system with hardware UART and software SPI vs my homebrew system with hardware SPI and (potential) software UART
@weirdboyjim8 ай бұрын
Lol, people seem to be pushing me towards adding at least a partial implementation in hardware.
@RooMan938 ай бұрын
As we're using console accessories, a PS1(2) Memory Card would be fun, it uses SPI with a couple of quirks.
@bzuidgeest8 ай бұрын
That's not a bad idea. Those are cheap as can be and you could basically treat them as a flash cartridge.
@weirdboyjim8 ай бұрын
Interesting idea, I like it but there doesn't seem to be an easy way of getting data on/off from a pc.
@RooMan938 ай бұрын
@@weirdboyjim I hadn't thought that far ahead to be honest
@segfault-berlin8 ай бұрын
yes please do a full SPI circuit.
@weirdboyjim8 ай бұрын
Seems to be a lot of call for it!
@TLang-el6sk8 ай бұрын
Personally I would go for a partial implementation. I'm doing professional development of embedded software for typical automotive and mainstream ARM controllers for nearly 30 Years now and the "full" implementations of many of these controllers are very limited, especially when it comes to word lengths and bitrate settings. So as soon as you have some hardware that e. g. requires 24bit or 32bit transfers (a collegue of mine currently is fighting with an ADC requiring these) you may have to turn of all the nice automatic features and fire the data by software. It's not bitbanging but still you will have a higher CPU load. And exactly this is the level I would implement: Clock out the data of let's say an 8 bit word automatically, perhaps add another byte as buffer and do the rest by code.
@weirdboyjim8 ай бұрын
Thanks for the input. There seems to be some very different ideas on what would constitute a full implementation but for me just something that can stream 8-bits in/out without manually toggling the clock line would tick a lot of boxes!
@TheEmbeddedHobbyist8 ай бұрын
Nice to check the OSF flag before a reading the time or date, so you have an indication whether you can trust the data. Oscillator Stop Flag (OSF). A logic 1 in this bit indicates that the oscillator has stopped or was stopped for some time and may be used to judge the validity of the clock and calendar data.
@weirdboyjim8 ай бұрын
Yeah but I wanted to keep this about SPI rather than the idiosyncrasies of that chip. After recording I switched it to a multi byte read which I believe is the other way to solve that issue. For anyone reading this comment, the issue TEH is referring to relates to when the time or date counters roll over between reads. So for example if I read the minutes then the seconds as the rollover is occurring from 2:59 I might read 2:00.
@TheEmbeddedHobbyist8 ай бұрын
Well not quite the OSF flag lets you know if the oscillator as stopped at some point in time before you have read the chip. if set the time can not be trusted as you have no idea how long the oscillator has stopped, I.E. your back-up battery might have dropped below the voltage level to support a stable clock. I check this when I power up the circuit and before I read the time, if set I go and attach to my wifi and get the correct time and date from a time serer and reprogram the RTC. @@weirdboyjim
@colinstu8 ай бұрын
I'd like to see either implementation! start w/easy one first, and assess from there if full is needed still.
@weirdboyjim8 ай бұрын
Yeah, I think incremental building makes for a better learning experience!
@ExtremeMetal8 ай бұрын
Am I right in thinking the SPI protocol allows for accessing SD cards?
@weirdboyjim8 ай бұрын
SD Cards can indeed be accessed via SPI although they run at a different voltage.
@wadowicegwadowiceg80938 ай бұрын
To me, I'd love to see octalSPI or QuadSPI. Probably too much for 8-bit computers, but easy to do with bit-banging. Good job !
@weirdboyjim8 ай бұрын
I've thought those variants should be called PPI!
@hola35358 ай бұрын
Uff, this is a complex situation, for one part we want something simple, but for the other part we want something that fullfill all of owr spectations.
@weirdboyjim8 ай бұрын
That's always the problem!
@rickdearman99928 ай бұрын
Wow. I have researching SPI and bit banging. Coincidence
@weirdboyjim8 ай бұрын
Hope what I've done is useful!
@johansteenkamp92148 ай бұрын
Also would loke to see a full SPI implementation. Curious to know: are you going to make an implemtation that allows to promatically switch between the differerent SPI modes (0-3), or are you just going to swop out wires if you encounter an SPI device that needs a different SPI mode?
@weirdboyjim8 ай бұрын
Ideally I'd have a couple of spi devices at a time so I'd need to at least support the modes they require,
@khatharrmalkavian33068 ай бұрын
SNEScon is just a pair of shift registers, and those do play nice with SPI. Enough so that a shift register and a few logic gates are all you need for an SPI bus controller.
@weirdboyjim8 ай бұрын
Similar yes, but the latch line doesn't work quite like the chip select line.
@khatharrmalkavian33068 ай бұрын
For a 595 you can just put an inverter on cs and run it to the latch. The same line can disable all the devices attached to the bus, so cs on means write to the register, then cs off means that the target device(s) selected, based on whatever was written to the register.
@Stabby6668 ай бұрын
If you were willing to accept a small compromise of streaming in blocks of 256 bytes at a time, you could load data at 4mhz directly to RAM using a few chips: A shift-in parallel out connected to the SPI sub (I'll assume flash memory here) An 8 bit counter with bit 3 used to latch the data in the above register to its output, and reset this counter An 8 bit counter with its outputs on the low 8 bits of the data bus (of course you could use 2 of these, to allow loading up to 64k blocks) This would require some way to disconnect the CPU from the data and address bus during the transfer - the old ZX81 (I believe) used resistors so that the data bus could be overridden on the CPU side of the resistors to the NOP instruction whilst drawing the screen. So the set up would use a normal SPI write to set the read address from the SPI flash chip, then using one of the unused bits of the GPIO output to initiate the DMA transfer, with some sequence like: 1. Set a latch to force NOPs on the data bus of the CPU 2. Force the high 8 bits of the address bus to a fixed value 3. Reset the two counters. Then each clock would read a bit from the SPI flash into the shit-in register, and after 8 clocks the first counter would latch the output into RAM, and reset itself (which would also reset the latch) then via a slight delay circuit, increment the memory address counter register. This would continue until the overflow of the address counter register, which could signal the end of the transfer and release the forced NOP from the CPU, allowing it to continue. Of course you could reuse most of that to also stream data out if you wanted, but I guess that's not really needed so much for games! The bus arbitration would be a couple of parts, but I guess this all depends on if you want to load in 256 bytes in under 1/2 a millisecond :) Obviously this is at 4mhz - I cant remember if you use a clock divider on your main crystal, but obviously this could run as fast as the SPI flash/RAM can handle the transfers.
@weirdboyjim8 ай бұрын
I think you can get to the full 4mhz without anything as complex as you describe here. The challenge is to do it with as simple a system as possible working within the limitations of the underlying system.
@Stabby6668 ай бұрын
@@weirdboyjim yep it was a bit late when I typed that and later thought you only really need a shift in and shift out register with the main clock fed into both and cycle accurate code to handle latching and loading/storing the data at the full rate 😁
@edgeeffect6 ай бұрын
Yeah in the UK we do dates backwards which is better than some places, where they do them inside-out. ;)
@weirdboyjim6 ай бұрын
Sadly "Number of seconds since January 1, 1970" didn't catch on with the general public.
@vmiguel19888 ай бұрын
You will also need to accommodate clock speed setup since different devices can operate in different clocks, probably a register/counter/comparator schema, I guess that is what going to consume more logic.
@weirdboyjim8 ай бұрын
Fortunately the need for variable clock speeds is limited, my "high speed" clock of 4mhz is pretty low in the grand scheme of modern electronics.
@peter.stimpel8 ай бұрын
If I was you, I would not go for the last bit of every integration now, just what you need for the moment, with room for improvement. But that's me only.
@weirdboyjim8 ай бұрын
I do have a habit of going down rabbit holes, but we probably wouldn't be here if I didn't.
@kilianhekhuis7 ай бұрын
What you should watch out for, is that interfacing with a full hardware implementation of SPI could end up being as much code as interfacing with a partial implementation.
@weirdboyjim7 ай бұрын
I agree, the definition of "full implementation" is also pretty vague. I'm interested in finding the sweet spot to get a decent transfer rate.
@TheEmbeddedHobbyist8 ай бұрын
This type of data transmission is so easy to bit bang, this goes of any form of well documented data transfer, I much prefer this than RS232. Reading RS232 where you can have no idea of how many characters are coming , whether they will end with CR/LF or LF/CR. even down to if the sending Baud rate is the same as your receiving rate even when they are set the same. Can't beat a nice preamble to lock your clocks. 🙂
@weirdboyjim8 ай бұрын
Why use one wire when you can use 3! 😅
@TheEmbeddedHobbyist8 ай бұрын
Well Rs232 is two wire but who's splitting hairs. 🙂@@weirdboyjim And of course SPI always +1 as you need a ground reference.
@sanderspeetjens8 ай бұрын
I would like to see a hardware implementation instead of bit banging. The reason is that I created a spi slave in VHDL but haven't seen a logic components version
@weirdboyjim8 ай бұрын
I'll definitely do some hardware work on it!
@frognik798 ай бұрын
The date is the 'correct' way around here in Australia. Why is it upside down though?
@weirdboyjim8 ай бұрын
It must be really difficult to read hour glasses down there!
@janschrder8 ай бұрын
Full SPI or a hybrid optimised for speed? Hmmmm... If You're not going to use SPI for a lot of different purposes, the latter of Your suggestions might be the most interesting one. I guess that I'll be leaning towards that one too :-)
@weirdboyjim8 ай бұрын
Yeah, I've been roughing out some ideas. I think I can get pretty close to 4mb/s read speed with the addition of 2 chips.
@janschrder8 ай бұрын
@@weirdboyjim That would be an interesting achievement 😎👍
@RegisMichelLeclerc8 ай бұрын
How much would it take to implement it fully in electronics instead of software? How much faster would it be? I know it's implemented in hardware in the ATMega8 (as well as I2C), which makes it piece of cake to interface small OLED screens (including color ones in 16 bits), and such thing is not really possible at 70K per second... Meanwhile (IIRC), an ATMega8 on an Arduino at 16MHz "limits" the bandwidth to 4MHz (f(osc)/4) as a slave, which would be more like 300KB/s (including protocol bits), which lets it do something else (such as reading the clock it displays, or reading the MPU6050 and calculate the display lines for a compass while sending orders to servo motors, read the position of the paddle to set the desired roll/yaw/pitch, etc.).
@weirdboyjim8 ай бұрын
My goal would be to use the system clock (4mhz), I think even a partial implementation could max out the data transfer rate to 4mbs.
@cj09beira8 ай бұрын
well as an example it took me 21 74 series chips to implement one which supports all permutations of SPI and bit order.
@tinygriffy8 ай бұрын
I am using SPI for years now and never bothered to _really_ understand it.. very comprehensive, thanks .. (If I had to use your Keyboard on my PC it would drive me crazy in milliseconds.. 😅🙈)
@weirdboyjim8 ай бұрын
Hope it was useful! My keyboard isn't a noisy as you think it is in person but the impact noises couple easily with the mic, and I do have a tendency to punch the enter key when I'm doing a run command.
@tinygriffy8 ай бұрын
@@weirdboyjim Oh, I see.. sound coupling.. well never mind then ! Yes, I think all of your Videos are relatively useful.. and entertaining ;) It is astonishing what kind of progress is happening there, I am watching since the start of the project ;)
@0toleranz8 ай бұрын
@@weirdboyjimI second that keyboard noise because I often watch your videos commuting from/to work on the iPad with AirPods on and especially this time I had to turn down the volume because the key-clack was so loud I barely could hear what you were saying. Could you just turn down the ambient noise? By using a 2nd mic most modern software should be able to do so. BTW the 74LS299 is probably the easiest way to implement a bidirectional spi ish interface. Implementing the 4 different modes needs probably the most additional silicon.
@DAVIDGREGORYKERR2 ай бұрын
What about using the INTEL 8251 for SPI
@weirdboyjimАй бұрын
I wanted to do this "from scratch", I'll use more off the shelf parts in the future. That said, I don't think the 8251 can do SPI.
@cj09beira8 ай бұрын
with SPI in, ENC80J60 says hello
@weirdboyjim8 ай бұрын
Eack, would not relish driving that with 64k of ram!
@3osufdh4rfg7 ай бұрын
SPI? Mentioning moving towards a storage solution? I'm guessing SD cards. Could be a flash chip with SPI too but that seems less useful.
@weirdboyjim7 ай бұрын
"You might very well think that; I couldn't possibly comment"
@TheEmbeddedHobbyist8 ай бұрын
How about putting the SPI hardware in to a PAL and do SPI to parallel transfers. kind of fitting with the era of the design.
@weirdboyjim8 ай бұрын
Still avoiding more complex programmable parts. Shouldn't be a complex circuit anyway!
@TheEmbeddedHobbyist8 ай бұрын
But PAL's and GAL's are on the low side of complex@@weirdboyjim
@AJB2K38 ай бұрын
Does the cryatal not need capacitors?
@weirdboyjim8 ай бұрын
I was surprised by that but the datasheet doesn't have them and it seems to work fine without.
@jensschroder82148 ай бұрын
Can't SD cards also be read via SPI? At least in MMC compatibility mode! It probably only takes a few shift registers to convert from SPI to 8 bits in parallel.
@weirdboyjim8 ай бұрын
It can indeed. The core of an spi circuit would be shift registers but the control circuitry adds a bit of complexity.
@bzuidgeest8 ай бұрын
So can PS1 memory cards. Their size fits the system better, but they are harder to read on desktop machines.
@weirdboyjim8 ай бұрын
@@bzuidgeest interesting….
@TheChrisSimpson8 ай бұрын
Do a full SPI!
@weirdboyjim8 ай бұрын
I'll think about it. 😅
@DavidLindes8 ай бұрын
17:27 - I don't see how it's annoying to call out how ISO 8601 is a thing. ;)
@weirdboyjim8 ай бұрын
What people find annoying the internet will never fail to surprise you!
@DavidLindes8 ай бұрын
@@weirdboyjim Fair. I mean, I admit I found it mildly annoying that you basically gave a plug for 8601 but then didn't use it. ;) [But I don't actually care, it's your thing!]
@bzuidgeest8 ай бұрын
I was actually disappointed you used bit banging. So yes please build a full spi peripheral. It's true you could load your memory in a second with bit banging. But.... The full system will have many peripherals it needs to control, not just the load. You need to monitor the gamepad, make sound, write graphics. All that will take CPU cycles. So 70kb per second is rather optimistic in a real scenario. Also if you are going to talk to an SD card or something, there is far more protocol overhead. So the number of actually transferred bytes will increase. Like the VGA having spirits to offload drawing, you might want to give the full spi hardware a buffer, so if you're busy doing something else transfers keep going and you can catch up later.
@weirdboyjim8 ай бұрын
I always like to break things down into logical steps. Bit Banging was a good place to start, I'll definitely add some hardware support.
@gammongaming90818 ай бұрын
should add scsi to the computer for data storage
@weirdboyjim8 ай бұрын
An idea, but probably over the top for an 8-bit system with 64k of ram!
@m1geo8 ай бұрын
Hardware SPI!
@weirdboyjim8 ай бұрын
I've been playing with some ideas, I think it would be possible to get a hybrid circuit to roughly max out the system clockrate (4mb/s) with very few chips and clever code. What would you expect from full spi?
@m1geo8 ай бұрын
@@weirdboyjim Haha, I mean, at work, 250 MHz clock, and sequential read/write. But that's not realistic out of discrete parts. Maybe 40 MHz is a good target, but no sense running the SCLK faster than you fill/take data. Will you be using anything with lots of memory? SDCard? Or is this just for slow peripherals? Either way, couple of shift registers, a control register, and maybe a clock divider register should have you covered?
@weirdboyjim8 ай бұрын
@@m1geo It would take me a minimum of 3 cycles to consume a byte and store it in memory. So spi clocked at over 10 mhz wouldn't really be of any use. I'd settle for clocking the spi at the system clock at 4mhz.
@m1geo8 ай бұрын
@@weirdboyjim 4 MHz sounds a good speed. Should be easy to get the logic to do that. Will you have read/write FIFO?
@weirdboyjim8 ай бұрын
@@m1geo Haven't decided exactly what I'm doing but there is not a great deal of cost/benefit to a fifo here.
@akkudakkupl8 ай бұрын
Master Out Slave In, Master In Slave Out. There is some stupid notion that people will be offended by mere existence of certain words, so we should change established nomenclature just to make those hypothetical individuals "safe". The problem is not in the nomenclature, but in the people who elect to get offended by anything and everything. I don't understand this trend at all.
@porklaser8 ай бұрын
These terms should be phased out because their origins unsavory and their continued use is both a distraction and poor taste. This argument has been settled decades ago. Catch up.
@rickyrico808 ай бұрын
Lots of software got broken when github had the brilliant idea to switch the master branche to main branche. The only people affected we're obviously not the people that had issue with masters or slaves but hey, progress I guess words are scary things for feeble minds.
@bzuidgeest8 ай бұрын
@@porklasertheir is nothing unsavory about the origins of the terms. They accurately describe the relation between two non sentient devices. It has nothing to do with slavery between humans. If you cannot separate your emotions from tech you have a problem. What's next, you going to fake your results to make them fit a religion? Or some other unprovable notion? Tech deals with facts, leave your politics at home.
@cj09beira8 ай бұрын
agreed, modern society really is in the "Weak men make hard times" part of the cycle
@porklaser8 ай бұрын
Techical debt punishes the lazy. Do you read your style guides?@@rickyrico80
@Xylarr6 ай бұрын
"Other geographies do it differently". No, one geography does it wrong - let's not beat around the bush.
@weirdboyjim6 ай бұрын
You might think that, I couldn't possibly comment. 😜
@jensschroder82148 ай бұрын
In Europa the order is day/month/year. In China year/month/day. In the US the order makes no sense: month/day/year
@weirdboyjim8 ай бұрын
Since recording the code I've been noticing all the places that do year-month-day regardless, I'll probably switch my code to that.
@luz_reyes_6768 ай бұрын
It makes sense !! its how we speak the date. how do yall speak aloud the date in conversation ?
@CollinBaillie8 ай бұрын
@@luz_reyes_676I came to make this comment. We pretty much say it as we write it also (day-month-year in Australia). We'll say the 25th of December, rather than December 25th.
@martinmckee53338 ай бұрын
@@luz_reyes_676In the US it is often spoken month-day-year, just as it's written here. Sometimes, more rarely someone will speak day-month or day-month-year. I don't think I've ever heard year-month-day spoken, though I have worked on some projects that have used it for file naming (primarily due to the sorting behavior).
@johnaldis98328 ай бұрын
@@luz_reyes_676 I say "the of ". So US Independence Day is "the fourth of July" for example. What do you call it? 🙂
@cjveeneman8 ай бұрын
Wiki changing Master/Slave to Main/Sub is very much intentional.
@weirdboyjim8 ай бұрын
Yes, but if you try to cover up that it was ever referred to as Master/Slave you make nonsense out of a lot of old documentation.
@AJB2K38 ай бұрын
The Master/Slave designations are being ruled out because of the Snowflake Generations!
@weirdboyjim8 ай бұрын
I'm just trying to keep everything factual.
@tomasparrado8738 ай бұрын
I don't care what they're called so long as it doesn't fall into the in/out or rx/tx trap. Main/sub works well and fits the classic miso/mosi acronym. Even host/client that i've seen in a few recent microchip datasheets is acceptable. I don't like the data in/data out convention whereby the nets swap name depending on which chip you're referencing. It's not a big issue, but the fewer silly ways to screw up a layout the better
@luz_reyes_6768 ай бұрын
i think its also that the field has matured and we can have more meaningful nomenclature
@bzuidgeest8 ай бұрын
@@weirdboyjimyou shouldn't have had to deal with it at all. I compliment you on putting the facts out there as they are. But the necessity of your explanation is caused by politics seeping into tech and that's just as bad as religion messing with science.
@bzuidgeest8 ай бұрын
@@tomasparrado873slave in this context had more meaning than sub can convey. The slave device follows the master, the master generates the clock. Slave in this regard said something about how dependent the sub device is. Sub does not convey that meaning at all.
@bussi78598 ай бұрын
Too crappy keyboard
@weirdboyjim8 ай бұрын
I like my keyboard.
@bussi78598 ай бұрын
Get a haircut
@weirdboyjim8 ай бұрын
I hope your strategy at social interaction works out for you.