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Forum Index : Microcontroller and PC projects : Hello and My PicoMite Build!

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g0730n
Newbie

Joined: 14/05/2025
Location: United States
Posts: 2
Posted: 09:22pm 14 May 2025
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I ended up building my PicoMite on a protoboard and used components I already had.

It all works great and all that is left to do is print a 3d case for it. The AC adapter for the laptop i use for all my printing failed recently so I am waiting for the new one in mail.

Features:
-VGA OUTPUT
-USB KEYBOARD
-DS3231 RTC
-DHT11 Temp/Humidity Sensor
-SD Card
-2 LEDS (GREEN = PLUGGED IN, POWER OFF), (RED = PLUGGED IN, POWER ON)
-Breakout pin header for unused GPIO (Currently not wired up)
-2 Passive Piezo Buzzers for audio output. I did not know if this would actually work for playing a WAV, but it does!
-Slide switch for Power
-RESET Button
-TP4056 LiPo Battery charger (I didn't have Micro USB breakout, so ended up using one of these for the breakout. I may implement a battery in future for something so there it is)




I used Pogo Pins for the USB D+ and D- to avoid soldering directly to pico test points, it actually seemed to work great!



My protoboard soldering work is never pretty, and takes about 10x longer than a PCB, but here are some more pics.





One thing I am wondering is if I can have any other serial devices attached if I also have SD Card installed on RP2040 VGA USB.

I would like to interface with an nrf24l01 possibly in the future.

But aside from that I am going to play around with writing some BASIC programs! The graphics capabilities of PicoMite are looking pretty awesome makes me want to make a small game.
 
dddns
Guru

Joined: 20/09/2024
Location: Germany
Posts: 334
Posted: 09:43pm 14 May 2025
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Well done!

sdcard and serial are completely different and yes, you can have a second serial port for your basic program to access. This is very good described in the manual appendix A and following.

Happy tinkering and try a 2350 for even more fun
Edited 2025-05-15 07:44 by dddns
 
stanleyella

Guru

Joined: 25/06/2022
Location: United Kingdom
Posts: 2397
Posted: 10:03pm 14 May 2025
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nice one
 
phil99

Guru

Joined: 11/02/2018
Location: Australia
Posts: 2434
Posted: 11:13pm 14 May 2025
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Welcome to the forum, making your own layout on protoboard or stripboard allows easy modification for new ideas.

Adding the nrf24l01 might require using the second SPI channel (SPI2) as I don't think the VGA versions support System SPI, which may have allowed sharing the SPI bus with the SD card.

Appendix D in the manual describes SPI.

Edit.
  Manual said  Dedicated I/O Pins
Alternatively, where no other devices share the SPI bus with the SD card it can be set up with:
OPTION SDCARD CS_pin, CLK_pin, MOSI_pin, MISO_pin
In this case the pins can be assigned completely flexibly and do not need to be capable of SPI operation but SD card performance will be better if valid SPI pins are chosen.


That a Chip Enable pin is used makes me wonder, despite that, if it is possible to use the same SPI as the SD card.
Someone who has tried it may let us know.
Edited 2025-05-15 09:35 by phil99
 
g0730n
Newbie

Joined: 14/05/2025
Location: United States
Posts: 2
Posted: 05:37am 15 May 2025
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  phil99 said  Welcome to the forum, making your own layout on protoboard or stripboard allows easy modification for new ideas.

Adding the nrf24l01 might require using the second SPI channel (SPI2) as I don't think the VGA versions support System SPI, which may have allowed sharing the SPI bus with the SD card.

Appendix D in the manual describes SPI.

Edit.
  Manual said  Dedicated I/O Pins
Alternatively, where no other devices share the SPI bus with the SD card it can be set up with:
OPTION SDCARD CS_pin, CLK_pin, MOSI_pin, MISO_pin
In this case the pins can be assigned completely flexibly and do not need to be capable of SPI operation but SD card performance will be better if valid SPI pins are chosen.


That a Chip Enable pin is used makes me wonder, despite that, if it is possible to use the same SPI as the SD card.
Someone who has tried it may let us know.


I usually make the first version of anything on breadboard > protoboard > then PCB. Usually the protoboard version because I want to make the first one without waiting for PCB, but yeah it does really help with adding/removing stuff.

That bit about the SD card on VGA version only available to SD card in manual was what got me confused. I think I was thinking that meant no other SPI was available, but it makes sense that the second bus is available.

The only version of BASIC I had used at this point is Arduino BASIC, where line numbers are needed in programs. I had a lot of fun with that. MMBasic is way more advanced and the little bit I have done on it so far is quite enjoyable!
 
Volhout
Guru

Joined: 05/03/2018
Location: Netherlands
Posts: 4875
Posted: 06:20am 15 May 2025
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The PICO has 2 SPI hardware blocks.
In the microcontroller version, you can assign SYSTEM SPI to one of these, and share the SPI bus between LCD , Touch, and SD card. Quite clever. The hardware SPI blocks however have designated pins.

In the VGA/HDMI version, there is no touch, no lcd, so the SPI is used only for SD card. To be flexible in what pins to use, the SD card (SPI) interface is "bit-banged". So every pin can be used for every SD card signal. So it is not using a hardware SPI block.

In the VGA version you potentially could have 2 free SPI blocks with carefull GPIO mapping. The microcontroller version has only 1 free SPI block.

Volhout
Edited 2025-05-15 16:21 by Volhout
PicomiteVGA PETSCII ROBOTS
 
Mixtel90

Guru

Joined: 05/10/2019
Location: United Kingdom
Posts: 7558
Posted: 07:10am 15 May 2025
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It's nice to see a board where the bottom side is neater than the top. ;)
That's a nice job and you've fitted a lot of stuff on there, congratulations.

I'd seriously considered getting some pogo pins for exactly this purpose. It was one of the options I looked at just before coming up with the 44-pin Pico system. I needed the extra two GPIO for that project though so I abandoned the pogos.
Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs
 
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