def _eeprom_spi_write_byte(
spi: busio.SPI,
csel: digitalio.DigitalInOut,
address: int,
data: int,
timeout: float = 1.0,
) -> bool:
# Make sure address is only one byte:
if address > 255:
return False
# Make sure data is only one byte:
if data > 255:
return False
# Wait for WIP to be low
if not _eeprom_spi_wait(spi, csel, timeout):
return False
# Enable writing
csel.value = False
spi.write(bytearray([EEPROM_SPI_WREN]))
csel.value = True
# Write to address
csel.value = False
spi.write(bytearray([EEPROM_SPI_WRITE, address, data]))
csel.value = True
return True
def _eeprom_spi_wait(
spi: busio.SPI, csel: digitalio.DigitalInOut, timeout: float = 1.0
) -> bool:
# Continually read from STATUS register
timestamp = time.monotonic()
while time.monotonic() < timestamp + timeout:
# Perfrom RDSR operation
csel.value = False
result = bytearray(1)
spi.write(bytearray([EEPROM_SPI_RDSR]))
spi.readinto(result)
csel.value = True
# Mask out and compare WIP bit
if (result[0] & (1 << EEPROM_SPI_WIP_BIT)) == 0:
return True
return False
def _eeprom_spi_read_byte(
spi: busio.SPI, csel: digitalio.DigitalInOut, address: int, timeout: float = 1.0
) -> Tuple[bool, bytearray]:
# Make sure address is only one byte:
if address > 255:
return False, bytearray()
# Wait for WIP to be low
if not _eeprom_spi_wait(spi, csel, timeout):
return False, bytearray()
# Read byte from address
csel.value = False
result = bytearray(1)
spi.write(bytearray([EEPROM_SPI_READ, address]))
spi.readinto(result)
csel.value = True
return True, result