I2C FRAM Reading And Writing

We highly encourage everyone to use our new Python package which is packed with features. This library is still supported, but is not recommended for new design.

The example below demonstrates how to read from and write to an I2C FRAM. Beyond that, it's also an excellent example of how to port an open-source Arduino library into a python script that can utilize the Binho Multi-Protocol USB Host Adapter.

This example is uses a 256Kbit I2C FRAM (MB85RC256V / Fujitsu) breakout board from our friends over at Adafruit. You can purchase it here.

from binhoHostAdapter import binhoHostAdapter
from binhoHostAdapter import binhoUtilities

MB85RC_DEFAULT_ADDRESS = 0xA0
MB85RC_SLAVE_ID = 0xF8

class Adafruit_FRAM_I2C:

	# CONSTRUCTOR
	def __init__(self, addr):

		self.framInitialised = False
		self.i2c_addr = addr

	# PUBLIC FUNCTIONS

	# initializes I2C and configures the chip
	# call this function before doing anything else
	def begin(self, adapter):

		self.hostAdapter = adapter

		# Make sure we're actually connected
		manufacturerID = 0
		productID = 0
		deviceInfo = [manufacturerID, productID]

		self.getDeviceID(deviceInfo)

		manufacturerID = deviceInfo[0]
		productID = deviceInfo[1]

		deviceFound = True

		if manufacturerID != 0x00A:
			print("Unexpected Manufacturer ID: " + str(deviceInfo[0]))
			deviceFound = False

		if productID != 0x510:
			print("Unexpected Product ID: " + str(productID))
			deviceFound = False

		# Everything seems to be properly initialized and connected
		self._framInitialised = True;

		return deviceFound

	# Writes a byte at the specific FRAM address
	def write8(self, framAddr, value):
		
		self.hostAdapter.startI2C(0, self.i2c_addr)
		self.hostAdapter.writeByteI2C(0, framAddr >> 8)
		self.hostAdapter.writeByteI2C(0, framAddr & 0xFF)
		self.hostAdapter.writeByteI2C(0, value)
		self.hostAdapter.endI2C(0)

	# Reads an 8 bit value from the specified FRAM address
	def read8(self, framAddr):

		self.hostAdapter.startI2C(0, self.i2c_addr)
		self.hostAdapter.writeByteI2C(0, framAddr >> 8)
		self.hostAdapter.writeByteI2C(0, framAddr & 0xFF)
		self.hostAdapter.endI2C(0)

		response = self.hostAdapter.readByteI2C(0, self.i2c_addr)

		data = response.split()

		if len(data) == 3:
			return int(data[2])
		else:
			return 0

	# Reads the Manufacturer ID and the Product ID frm the IC
	def getDeviceID(self, deviceInfo):

		self.hostAdapter.startI2C(0, MB85RC_SLAVE_ID)
		self.hostAdapter.writeByteI2C(0, 0xA0)
		self.hostAdapter.endI2C(0, True)

		response = self.hostAdapter.readBytesI2C(0, MB85RC_SLAVE_ID, 3)

		data =response.split()

		if len(data) == 5:
			deviceInfo[0] = (int(data[2]) << 4) + (int(data[3]) >> 4)
			deviceInfo[1] = ((int(data[3]) & 0x0F) << 8) + int(data[4])


# Change this to match your COMPort
default_commport = "COM27"

print("I2C FRAM Example using Binho Host Adapter")
print("v1.0 -- Jonathan Georgino <[email protected]>")
print

utilities = binhoUtilities.binhoUtilities()
devices = utilities.listAvailableDevices()

if len(devices) == 1:
	COMPORT = devices[0]
	print("Found 1 attached adapter @ " + devices[0])
	print
else:
	COMPORT = default_commport
	print("Found more than 1 attached adapter, using default port " + COMPORT)
	print

print("Opening " + COMPORT + "...")
print

# create the binhoHostAdapter object
binhoDevice = binhoHostAdapter.binhoHostAdapter(COMPORT)
binhoDevice.setNumericalBase('10')

binhoDevice.setOperationMode(0, 'I2C')
binhoDevice.setPullUpStateI2C(0, '1')
binhoDevice.setClockI2C(0, 1000000)

framMemory = Adafruit_FRAM_I2C(MB85RC_DEFAULT_ADDRESS)

if framMemory.begin(binhoDevice) == True:

	# found the I2C FRAM

	memData = [0 for x in range(32)]
	for i in range(32):
		memData[i] = framMemory.read8(i)

	print(memData)

	for i in range(32):
		framMemory.write8(i, i*2)

	for i in range(32):
		memData[i] = framMemory.read8(i)

	print(memData)

	binhoDevice.close()

else:
	# couldn't read the FRAM manufacturer and product ID bits
	print("I2C FRAM not identified... check your connections?")

For comparison's sake, you can see the Adafruit Arduino library that this example was ported from here.