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Forum Index : Microcontroller and PC projects : User Manual for the Picomite (draft)
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| lizby Guru  Joined: 17/05/2016 Location: United StatesPosts: 3311 |
The PIC32MX170 also isn't intended as a computer, but MMBasic for this much less powerful chip includes keyboard support. I think this was an important feature in all previous versions of MMBasic, and think its omission for the PicoMite was unfortunate. But the decision was not mine to make, and for us as users, it is what it is. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7512 |
I remember the PIC32MX170 having the KEYPAD command, so does the PicoMite, but no keyboard support... I'll dig my book out. :) The Micromite Plus to F4 had PS/2 keyboard support, not the Micromite. Without a quick parallel display there probably isn't much point in an external keyboard though. You'd be far better using an F4 than a PicoMite if you want something like that. Edited 2021-09-24 05:46 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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Poppy Guru Joined: 25/07/2019 Location: GermanyPosts: 486 |
I for myself am just pointing on VGA or something for a larger display, something like a 7" one. Of course the Pico and smaller clones are quite cute and specially a tiny display fits in very well ... What was still a F4?  Andre ... such a GURU? | ||||
| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7512 |
One of these: https://www.ebay.co.uk/itm/322268845458?hash=item4b08b85592:g:duYAAOSw5WNa2GeB No VGA though, but it can handle large parallel-driven displays. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3311 |
My mistake, sorry--MM+ has keyboard. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3311 |
Check out Armmite F4 on Fruit of the shed Up to 9" displays that I know of. ~ Edited 2021-09-24 07:25 by lizby PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| Poppy Guru Joined: 25/07/2019 Location: GermanyPosts: 486 |
Thanks. Also this issue is completely new for me being just concentrated on PICs as yet. Andre ... such a GURU? | ||||
Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3269 |
Thanks for the input guys. All the fixes have been applied and the manual updated to match the latest beta. You can download it from: https://geoffg.net/Downloads/PicoMite/PicoMite_User_Manual.pdf Let me know if you find any more bugs/typos/omissions/etc. Thanks, Geoff Edited 2021-09-24 15:56 by Geoffg Geoff Graham - http://geoffg.net |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7512 |
Thanks Geoff. Yet another excellently edifying opus! :) Page 8 The 120R resistor is limiting the current to approx. 12.5mA through the (assuming red Vf=1.8v and that the pin can reach 3.3v, which it may not be able to do) LED. That should probably be fine, but is right at the top limit for the pin. Modern LEDs shouldn't need anything like that to light brightly, and the apparent difference in brilliance as you reduce LED current is slight until you get a long way down. I would have preferred to have seen 150R (or even 330R) here to give a maximum red current of 10mA. That would keep below the 12mA max for the pin and still allow 8mA into a Vf=2.1v LED, which should be plenty even for stubborn LEDs. I read the note on driving LEDs on page 10, but personally I'm not happy about allowing the output voltage to sag too much under load as that will increase heat dissipation on the chip. It may be "within spec", but it still seems to be unnecessary. Incidentally, I got a box of assorted colour LEDs from China and all colours are plenty bright enough indoors and on axis (or just off) with 1k series resistors. That's only 1.3mA through a 2v LED. There's no reason to attempt to run modern LEDs at more than about 2mA, even 5mA is high. Edited 2021-09-24 18:14 by Mixtel90 Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3269 |
Actually 120R gives a current of 7.3mA due to the output of the Raspberry Pi Pico sagging, I normally aim for 5mA through a red LED so 220R is a better choice (4.9mA) while 680R (2mA) is hard to see in daylight. I am sure that there are LEDs that will be bright enough with less than 5mA but most LEDs that people have in their parts bin work well with that current. I will edit the manual to reflect that. Geoff Edit: I remember the days when 20mA was required!! Edited 2021-09-24 18:46 by Geoffg Geoff Graham - http://geoffg.net |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7512 |
lol - I still have some red LEDs that are so insensitive that 20mA is pushing it for them to be usable at all! I really should chuck them out... I know, I'll send them to you... ;) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 4854 |
I have blue leds in 0603 package here that need 10k otherwise they are too bright for the eye, at 3.3v PicomiteVGA PETSCII ROBOTS |
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led-bloon Senior Member  Joined: 21/12/2014 Location: AustraliaPosts: 207 |
Geoff Page 133 of Manual: PIO IRQ Flags The RP2040 datasheet section 3.2.6 is poorly worded. In fact what it is supposed to convey is: Each PIO block has 8 IRQ flags which are only available to the state machines of that block etc etc etc. Seems a bit of a waste. The simplest way to "signal" between blocks is to use a GPIO pin. Works ok. The hard way: Create a physical interrupt and get the core servicing that interrupt to send data to the other PIO block via FIFO. led Miss you George |
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| Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3269 |
Thanks led. Mixtel90 is doing the PIO part and I will thankfully leave him to figure that out. Geoff Geoff Graham - http://geoffg.net |
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| scruss Regular Member  Joined: 20/09/2021 Location: CanadaPosts: 88 |
But it's also correct, Seems there's been some issues with the homebrew diagram of the Raspberry Pi Pico. Overlay some mmbasic-specific labels and you're done. You'll also help people familiar with the Pico to understand mmbasic pin name mapping Some of the Pico VGA applications aren't toys: there are a couple of full computer emulations and a VTxxx terminal that use it. The BBC BASIC for Raspberry Pi Pico team are trying to provide the option of VGA output and leave some RAM free for the interpreter. |
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| Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3269 |
So, is our diagram incorrect now? You were looking at an earlier (beta) version. The reason for our own diagram is so that a BASIC programmer can find the pins using the naming conventions of the BASIC language. The intention is not to educate a purist who is familiar with the pin names used in other languages. Geoff Geoff Graham - http://geoffg.net |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7512 |
It certainly is confusing. And wrong! lol When I look at the list of registers it says that there are two base addresses, one for each PIO. They are PIO0_BASE and PIO1_BASE. The registers are then listed with an offset from those base addresses. According to that, the IRQ flags are at offset 0x030 so there has to be an IRQ register (8 flags) for each PIO, not one shared between PIOs. Please could you change the first sentence on page 133, Geoff? "The four state machines of a PIO have shared access to its block of 8 interrupt flags." Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7512 |
As far as I can see our pinout diagram is correct now. It isn't intended to tie in with the Raspberry Pi diagram because MMBasic can't use the Raspberry Pi signal names - we want MMBasic compatibility where possible. Overlaying RPi names would only cause confusion. I'm afraid that Python programmers will have to realize that they are programming in MMBasic. :) The RPi diagram also doesn't allow for the fact that we give the capability of redefining additional pins that that shows as dedicated. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| led-bloon Senior Member Joined: 21/12/2014 Location: AustraliaPosts: 207 |
Geoff or Mick In case you missed it: Manual correction to pinctrl helper function led Edited 2021-09-30 18:53 by led-bloon Miss you George |
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| led-bloon Senior Member Joined: 21/12/2014 Location: AustraliaPosts: 207 |
Got a Sparkfun pico pro micro: An interesting spin-off with extra flash, fewer accessible pins and an onboard WS2812 LED device. No great benefits, as far as the PicoMite software is concerned, apart from size of the board, probably enough pins to do the job that you want it to do. USB C connector, single-side components, castellated edge connections etc etc. An interesting device. Which leads me to... Updates to the manual. WS2812 support page 34: Spelling: "...BITBANG WS8212..." Bitbang function: Bitbang WS2812 Type, pin, count, colours%() ^^^^^^ (missing - count, num_LEDs, num_devices...whatever) led PS: No kickbacks from Sparkfun (obviously) Edited 2021-09-30 19:24 by led-bloon Miss you George |
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