rp_adc_test.py

# Pico MicroPython: ADC test code
# See https://iosoft.blog/pico-adc-dma for description
#
# Copyright (c) 2021 Jeremy P Bentham
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

import time, array, uctypes, rp_devices as devs

# Fetch single ADC sample
ADC_CHAN = 0
ADC_PIN  = 26 + ADC_CHAN

adc = devs.ADC_DEVICE
pin = devs.GPIO_PINS[ADC_PIN]
pad = devs.PAD_PINS[ADC_PIN]
pin.GPIO_CTRL_REG = devs.GPIO_FUNC_NULL
pad.PAD_REG = 0

adc.CS_REG = adc.FCS_REG = 0
adc.CS.EN = 1
adc.CS.AINSEL = ADC_CHAN
adc.CS.START_ONCE = 1
print(adc.RESULT_REG)

# Multiple ADC samples using DMA
DMA_CHAN = 0
NSAMPLES = 10
RATE = 100000
dma_chan = devs.DMA_CHANS[DMA_CHAN]
dma = devs.DMA_DEVICE

adc.FCS.EN = adc.FCS.DREQ_EN = 1
adc_buff = array.array('H', (0 for _ in range(NSAMPLES)))
adc.DIV_REG = (48000000 // RATE - 1) << 8
adc.FCS.THRESH = adc.FCS.OVER = adc.FCS.UNDER = 1

dma_chan.READ_ADDR_REG = devs.ADC_FIFO_ADDR
dma_chan.WRITE_ADDR_REG = uctypes.addressof(adc_buff)
dma_chan.TRANS_COUNT_REG = NSAMPLES

dma_chan.CTRL_TRIG_REG = 0
dma_chan.CTRL_TRIG.CHAIN_TO = DMA_CHAN
dma_chan.CTRL_TRIG.INCR_WRITE = dma_chan.CTRL_TRIG.IRQ_QUIET = 1
dma_chan.CTRL_TRIG.TREQ_SEL = devs.DREQ_ADC
dma_chan.CTRL_TRIG.DATA_SIZE = 1
dma_chan.CTRL_TRIG.EN = 1

while adc.FCS.LEVEL:
    x = adc.FIFO_REG
    
adc.CS.START_MANY = 1
while dma_chan.CTRL_TRIG.BUSY:
    time.sleep_ms(10)
adc.CS.START_MANY = 0
dma_chan.CTRL_TRIG.EN = 0
vals = [("%1.3f" % (val*3.3/4096)) for val in adc_buff]
print(vals)

# EOF