def read_flash(self, start, len):
crc = CRC()
print "Reading " + str(len) + " bytes from address " + hex(start)
data = self.spi_read(start, len)
crc.process(data)
local_crc = crc.get_crc()
dev_crc = self.spi_compute_crc(start, start + len - 1)
if (local_crc != dev_crc):
print "CRC validation failed! Expected " + hex(
local_crc) + ", received " + hex(dev_crc)
return None
return data
def write_segment(self, address, data):
crc = CRC()
length = len(data)
# unprotect the status register
self.spi_common_command(self.SPI_CMD_WRITE_AFTER_EWSR, 0x01, 0, 1, 0)
# unprotect the flash
self.spi_common_command(self.SPI_CMD_WRITE_AFTER_WREN, 0x01, 0, 1, 0)
if (self._should_program_page(data)):
# set program size - 1, 255 maximum
self._i2c_write_reg(0x71, (length - 1) & 0xFF)
# set the programming address
self._i2c_write_reg(0x64, (address >> 16) & 0xFF)
self._i2c_write_reg(0x65, (address >> 8) & 0xFF)
self._i2c_write_reg(0x66, (address >> 0) & 0xFF)
# write the content to register 0x70
# we can only write 16 bytes at a time
for i in range(0, length, 16):
if (length - i >= 16):
self._i2c_write_bytes(0x70, data[i:i + 16])
else:
self._i2c_write_bytes(0x70, data[i:i + length - i])
# start programming
self._i2c_write_reg(0x6F, 0xA0)
crc.process(data)
if (not self._wait_write_done()):
return False
local_crc = crc.get_crc()
dev_crc = self.spi_compute_crc(address, address + length - 1)
if (local_crc != dev_crc):
print "CRC validation failed! Expected " + hex(
local_crc) + ", received " + hex(dev_crc)
return False
return True
