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Forum Index : Microcontroller and PC projects : PICO 2W - MMBASIC - Trying to read analog joystick on ADC0 and ADC1
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| Askjerry Newbie  Joined: 21/09/2025 Location: United StatesPosts: 11 |
I have been tinkering with this for a couple hours now... using GEMINI AI which is usually pretty good... but getting one failure after another. In a perfect world, I would have two variables Jx and Jy, which would connect to ADC0 and ADC1, I'd read them maybe 10 times a second or so, and use the variables to do stuff. The last attempt was... ' Define variables DIM JX AS FLOAT DIM JY AS FLOAT ' 1. Configure the pins as their ADC Channel ' Use the special syntax SETPIN <pin_number>, ADC<channel_number> ' GP26 is ADC Channel 0. SETPIN 26, ADC0 ' GP27 is ADC Channel 1. SETPIN 27, ADC1 ' --- Main Loop --- DO ' 2. Read the analog voltage using the PIN function (Single Argument) ' Once configured as an ADC channel, PIN(n) should return the voltage. JX = PIN(26) JY = PIN(27) ' Display the values (JX and JY should be voltages from 0.0 to 3.3V) PRINT "JX (GP26/ADC0): "; JX; "V", "JY (GP27/ADC1): "; JY; "V" ' Wait for 0.1 seconds PAUSE 100 LOOP Of course it's failing... anyone have any code that works? Jerry |
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TassyJim Guru  Joined: 07/08/2011 Location: AustraliaPosts: 6338 |
SETPIN GP26, AIN SETPIN GP27, AIN You can refer to pins by their GPxx number or physical pin number. With the proliferation of boards, it is safest to refer by GPxx On a 'normal' pico board, pin 31 = GP26 ADC0 and ADC1 mean nothing to MMBasic. They are assumed to be a variable. If you always use OPTION EXPLICIT, that will be evident. Next time you are talking to Gemini, tell him/it to read the manual! Jim Edited 2025-09-28 07:05 by TassyJim VK7JH MMedit |
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| Askjerry Newbie Joined: 21/09/2025 Location: United StatesPosts: 11 |
I could have sworn that I tried doing a SETPIN GP26, AIN and that I got an error... But it's working well... SetPin GP26, AIN SetPin GP27, AIN Do Print Pin(GP26), Pin(GP27) Loop On the X-Axis I get 0.95 to 3.07 with 1.67 being the center, and on the Y-Axis I get 0.26 to 3.16 with 1.84 being the center. Interesting... in Thonny I was getting a range that was much larger... about 12 bits. Probably a difference in how BASIC is reading the data. This revision works... ' JOYSTICK EXPERIMENT - ADC0 and ADC1 ' Define Pins as inputs SetPin GP26, AIN SetPin GP27, AIN ' Start working with the TFT Display CLS Do text 220,10," JOYSTICK READINGS: "+ FORMAT$(Pin(GP26),"%.2f") + " , " + FORMAT$(Pin(GP27),"%.2f"),CM,2,,RGB(white),RGB(blue) Pause 0.0100 loop end Edited 2025-09-28 09:04 by Askjerry |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8232 |
Using PRINT PIN(GP26) will display the voltage relative to AVREF that's on the pin. So, if you use a LM4040 3V0 on AVREF and OPTION VCC 3 then GP26 will read from 0.0 to 3.0, with the mid point at 1.5. These are all floating point numbers, of course. By default AVREF is tied to the 3V3 supply on the Pico so the mid point will be at about half the VCC rail, normally around 1.65. The accuracy of the centre point depends on the pots on the joystick. Few are accurate and the more expensive joysticks include trimmers. You can also compensate in software, of course. :) Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| Askjerry Newbie Joined: 21/09/2025 Location: United StatesPosts: 11 |
This is the joystick that is part of the breakout board. BREAKOUT BOARD Edited 2025-09-29 02:27 by Askjerry |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 8232 |
I refuse to guess then. :) That's how MMBasic reads ADC inputs anyway. You get a voltage and it's up to you what you do with it. I usually scale it so that I get 0-100% of travel by multiplying the voltage by (100/3.3). Some fiddling with the endpoint voltages that you read centres it up. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10531 |
You can use SETPIN n,ARAW to get numbers in the range 0-4095 (manual page 153) Edited 2025-09-29 03:43 by matherp |
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