def query(slave_name, command, args=[]):
"""Selects the given SPI slave, sends it the SPI command and returns the received response as a
stripped string.
@param slave_name: _KNOWN_SPI_SLAVES key.
@param command: _KNOWN_SPI_SLAVES[slave_name]['commands'] key.
@param args: list of strings to be sent as command arguments.
"""
_select_spi_slave(slave_name)
spi = SPI(_SPI_BUS_SETTINGS['dev'], _SPI_BUS_SETTINGS['mode'], _SPI_BUS_SETTINGS['freq_hz'])
full_command = _KNOWN_SPI_SLAVES[slave_name]['commands'][command]
if args:
full_command += ' ' + ','.join(args)
full_command += '*' + int_to_hex_string(_crc(full_command))
full_command = (bytes(full_command, 'ascii') + _SPI_MESSAGE_SEPARATOR).ljust(_SPI_COMMAND_LENGTH,
b'\x00')
response = spi.transfer(full_command)
response = response.split(_SPI_MESSAGE_SEPARATOR)[0]
spi.close()
printable_response = ''.join(map(lambda ascii_num: chr(ascii_num),
filter(lambda char: char >= 0x20 and char < 0x7f, response)))
return printable_response
class MCP3208(object):
MAX_CLOCK_SPEED = 2E+6
RESOLUTION = 0b1 << 12
SECOND_WORD_MASK = 0b00001111
def __init__(self):
self.spi = SPI(
config.get('MCP3208', 'device_file'),
0,
MCP3208.MAX_CLOCK_SPEED
)
self.Vref = config.getfloat('MCP3208', 'vref')
def read(self):
mosi_data = self._make_mosi_data()
miso_data = self.spi.transfer(mosi_data)
_, second_word, third_word = miso_data
value = ((MCP3208.SECOND_WORD_MASK & second_word) << 8) + third_word
return value * self.Vref / MCP3208.RESOLUTION
def clean_up(self):
self.spi.close()
def _make_mosi_data(self):
ch = config.getint('MCP3208', 'ch')
raw_data = 0b0000011000 + ch
first_word = (0b11100 & raw_data) >> 2
second_word = (0b11 & raw_data) << 6
return [first_word, second_word, 0b0]
#analyze
from periphery import SPI
spi = SPI("/dev/spidev0.0", 1, 500 * 1000)
buff = [0x03, 0x0E, 0xFF]
txt = input("address in hex(default 0x0E):")
if txt != "":
buff[1] = int(txt, 16)
result = spi.transfer(buff)
print("register address:0x%02X -- value:0x%02X" % (buff[1], result[2]))
spi.close()
#device tree SPI without CS
from periphery import SPI
from periphery import GPIO
CS = GPIO("/dev/gpiochip0", 12, "out")
spi = SPI("/dev/spidev0.0", 1, 1000000)
tx = [0x02, 0x0F, 0x80]
rx = [0x03, 0x0E]
CS.write(False)
spi.transfer(tx)
CS.write(True)
CS.write(False)
#!/usr/bin/python3
from periphery import SPI
import time
spi = SPI("/dev/spidev0.0", 0, 10000)
while 1:
data=spi.transfer([0])
print(data)
time.sleep(0.1)
spi.close()