"resource not available" when assigning P9 / G16 as ADC
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Hello,
After much headache I discovered this post (https://forum.pycom.io/topic/313/lopy-pin-out/3)
where one user says that it's possible to find the correlation between chip pins and expansion board pins with a REPL command.
And so I found out that P9 on the chip is G16 on the expansion board and this pin should have ADC capability.So I wrote in my code:
adc = machine.ADC()
sensorPin = adc.channel(pin="P9")But it keeps throwing a "OSError: resource not available" on that second line. I did import machine.
What is this supposed to mean? That P9 is not G16 after all, or despite this diagram (https://docs.pycom.io/chapter/datasheets/downloads/lopy-pinout.pdf) saying that P9 has ADC, it does not? Or that some other feature on this port prevents me from using it?
EDIT: after making sure I wasn't using ADC2 ( the ones on the left side), I got rid of this error for some time. Now it's come back, and it doesn't matter which pin I use: ADC is just not available as a resource, and I'm getting no clue what so ever as to why this is..
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@robert-hh
Hey Robert! Good to see you're still around. Not back at Pycom but some collaboration brewing up, watch this space ;-)
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@jmarcelino Hello Jose. Are you back again?
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@jmarcelino Thank you, noted. Will design accordingly.
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@HenroRitchie
I've not followed the Pycom developments too closely but at low level ADC2 is only available when WiFi is off "ADC2 is used by the Wi-Fi driver. Therefore the application can only use ADC2 when the Wi-Fi driver has not started."My guess is this complicates things in a dynamic Python environment where you can turn WiFi on and off at will so probably not a priority.
To be honest ADC1 is quite noisy so I avoid the ESP32 ADCs altogether and now use a more "industrial grade" external solution.
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@jmarcelino Is this still the case. I am trying to access ADC2 on a Lopy4 and get the same error
OSError: resource not available. ADC1 seems to be working fine.
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@robert-hh yes, sorry i know - I have been trying with the following pins with that code i send you now: "13, 14, 15 and 23". 13, 14 and 15 is adc1.
I think maybe I understand the problem a tiny bit better now:
it happens only when I'm doing a soft reset. When I do a hard reset, it works again. Is this because a soft reset doesn't free up the pins maybe?
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@soren P23 belongs to ADC2 ..... You should write P14, or G4, like you state in the comment
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Hi robert, as far as I can tell - I'm doing the same thing as you.. here is my code, it's on line 9 ("sensorPin = adc...) it reports this error:
import machine from machine import Pin import time import pycom from machine import ADC from machine import PWM adc = machine.ADC() sensorPin = adc.channel(pin='P23', attn=ADC.ATTN_11DB) # G4 on expansion board ledArray = [0x7f0000, 0x007f00, 0x0000ff] # red, green, blue step_p = Pin('P8', mode=Pin.OUT) stepDir_p = Pin('P21', mode=Pin.OUT) class ColorSensor: dosingPump_p = Pin('P21', mode=Pin.OUT) dosingPump_p.value(0) # SERVO: pwm = PWM(0, frequency=50) servo_p = pwm.channel(0, pin='P22', duty_cycle=0.127) servo_p.duty_cycle(0.107) # 0.107 # upright position # 0.03 # pouring position balanceSet = False colourArray = [0, 0, 0] whiteArray = [0, 0, 0] blackArray = [0, 0, 0] avgRead = 0 def checkBalance(self): print("checking balance") if not self.balanceSet: self.setBalance() def setBalance(self): print("setting balance") time.sleep(5) for num in range(0, 3): # set white bal print(num) pycom.rgbled(ledArray[num]) # set to color time.sleep(0.1) self.getReadings(5) self.whiteArray[num] = self.avgRead print('avgRead from bal ', self.avgRead) pycom.rgbled(0x000000) # turn off led time.sleep(0.1) time.sleep(5) for num in range(0, 3): # set black bal pycom.rgbled(ledArray[num]) time.sleep(0.1) self.getReadings(5) self.blackArray[num] = self.avgRead pycom.rgbled(0x000000) # turn off led time.sleep(0.1) self.balanceSet = True time.sleep(5) def checkColour(self): print("rinsing...") for num in range(0, 3): # rinse glass 3 times dosingPump_p.value(1) # take in water from aquarium time.sleep_ms(500) # how much water to take in? dosingPump_p.value(0) # turn off dosing pump time.sleep(1) servo_p.duty_cycle(0.03) # pour out water time.sleep(4) servo_p.duty_cycle(0.107) # turn back glass time.sleep(4) print('rinsing finished! Taking in water...') dosingPump_p.value(1) # take in water from aquarium time.sleep_ms(500) # how much water to take in? dosingPump_p.value(0) # turn off dosing pump time.sleep(1) print('taking plunger down...') for num in range(0, 201): # take plunger down step_p.value(1) time.sleep_ms(500) step_p.value(0) time.sleep_ms(500) # check if plunger is all the way down and break ? print('plunger is down! Waiting for analysis...') time.sleep(1) # set to 3 minutes print('analysis ready! Reading colours...') for num in range(0, 3): pycom.rgbled(ledArray[num]) # set to color time.sleep(0.1) self.getReadings(5) self.colourArray[num] = self.avgRead print('whitearray ', self.whiteArray[num], ' blackArray ', self.blackArray[num]) greyDiff = self.whiteArray[num] - self.blackArray[num] print('greydiff: ', greyDiff) self.colourArray[num] = (self.colourArray[num] - self.blackArray[num])/(greyDiff)*255 pycom.rgbled(0x000000) # turn off led time.sleep(0.1) def printColour(self): print('printing colour') return self.colourArray[0], self.colourArray[1], self.colourArray[2] def getReadings(self, times): reading = 0 tally = 0 for num in range(0, times+1): reading = sensorPin() print('reading ', reading) tally = reading + tally time.sleep(0.01) self.avgRead = (tally)/times print('avgRead ', self.avgRead) #print('avgRead ', avgRead)
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@soren Are sou sure? I can do it here.
import machine adc = machine.ADC() sensorPin = adc.channel(pin="P14")
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@jmarcelino so now I'm also getting this error from ADC1 pins... P14, to be precise
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@jmarcelino thank you very much for chiming in. i'm baffled why this isn't stated in capital letters on the official pinout diagrams
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@soren
The ADC2 pins are not available from Python, at least for the time being. You can only use ones starting with ADC1_...
