def transfer_value(value):
"""Reads and writes one byte from and to the SPI.
@var value: the byte to write
@return: the byte that was read
"""
# clear the TX and RX fifos
regs.SPI0CS |= 0x30
# set the TA flag
regs.SPI0CS |= 0x80
# wait for TXD flag
while regs.SPI0CS & 0x40000 == 0:
utils.nanosleep(0, 5)
# write the value to the TX fifo
regs.SPI0FIFO = value & 0xFF
# wait for DONE flag to be set
while regs.SPI0CS & 0x10000 == 0:
utils.nanosleep(0, 5)
# read the received value
value = regs.SPI0FIFO
# clear the TA flag
regs.SPI0CS &= 0xFFFFFF7F
return value
def configure(gpio, pull):
'''Configures the pull-up/down for the specified GPIO pin.
@param gpio: the number of the GPIO pin
@param pull: set to True to enable pull-up,
False to enable pull-down or
None to disable the pull function.
'''
if gpio < 0 or gpio > funcs.MAX_GPIO:
raise Exception('Invalid GPIO number')
if pull: # pull-up
regs.GPPUD = 2
elif pull is False: # pull-down
regs.GPPUD = 1
else: # None - disable pull
regs.GPPUD = 0
utils.nanosleep(0, 5)
reg_no = gpio // 32
bit_no = gpio % 32
if reg_no == 0:
regs.GPPUDCLK0 = 1 << bit_no
else:
regs.GPPUDCLK1 = 1 << bit_no
utils.nanosleep(0, 5)
regs.GPPUD = 0
utils.nanosleep(0, 5)
if reg_no == 0:
regs.GPPUDCLK0 = 0
else:
regs.GPPUDCLK1 = 0
utils.nanosleep(0, 5)
def transfer_values(values):
"""Reads and writes more bytes from and to the SPI.
@var values: the list of bytes to write
@return: the bytes that were read
"""
# clear the TX and RX fifos
regs.SPI0CS |= 0x30
# set the TA flag
regs.SPI0CS |= 0x80
read_values = []
for value in values:
# wait for TXD flag to be set
while regs.SPI0CS & 0x40000 == 0:
utils.nanosleep(0, 5)
# write the value to the TX fifo
regs.SPI0FIFO = value & 0xFF
# wait for RXD flag to be set
while regs.SPI0CS & 0x20000 == 0:
utils.nanosleep(0, 5)
# read the received value
read_values.append(regs.SPI0FIFO)
# wait for DONE flag to be set
while regs.SPI0CS & 0x10000 == 0:
utils.nanosleep(0, 5)
# clear the TA flag
regs.SPI0CS &= 0xFFFFFF7F
return read_values
