HydraFW Binary I2C mode guide

#HydraFW binary I2C mode guide

This guide is updated towards firmware release HydraFW v0.7 Beta: HydraFW (HydraBus) v0.7-beta-0-gc5567bd 2016-04-16

##Commands Once the I2C mode has been selected, the following commands are available :

• 0b00000000 Return to main mode. Returns BBIO1
• 0b00000010 I2C start bit
• 0b00000011 I2C stop bit
• 0b00000100 I2C read byte
• 0b00000110 I2C ACK bit
• 0b00000111 I2C NACK bit
• 0b00001000 I2C Write-then-read
• 0b00001111 Sniff all I2C traffic
• 0b0001xxxx Bulk I2C write
• 0b01000x00 Configure I2C peripheral
• 0b011000xx Set I2C speed

##Command details

###I2C start bit (0b00000010) Send an I2C start bit. Returns 0x01

###I2C stop bit (0b00000011) Send an I2C stop bit. Returns 0x01

###I2C read byte (0b00000100) Reads a byte from the I2C bus, returns the byte. You must ACK or NACK each byte manually!

###I2C ACK bit (0b00000110) Send an I2C ACK bit after reading a byte. Tells a slave device that you will read another byte. Returns 0x01

###I2C NACK bit (0b00000111) Send an I2C NACK bit after reading a byte. Tells a slave device that you will stop reading, next bit should be an I2C stop bit. Returns 0x01

###I2C Write-then-read (0b00001000) This command is used to send at most 4096 bytes and will read at most 4096 bytes of data. Format :

Byte 1           2          3          4          5         6        ...
|----------|----------|----------|----------|----------|----------|------...
 [command ] [   Bytes to write  ] [   Bytes to read   ] [ Data to write

The bytes to read/write are in little-endian format.

• All data will be buffered before being sent to the I2C bus. Read data will also be buffered on the Hydrabus before being sent back to the user.
• I2C start bit is sent before sending the data.
• All read bytes are ACKed, except the last byte which is NACKed.
• At the end of the read process, Hydrabus sends an I2C stop.

More information can be found here : http://dangerousprototypes.com/docs/I2C_(binary)#0x08_-_Write_then_read

###Sniff all I2C traffic (0b00001111) To be done

###Bulk I2C write (0b0001xxxx) In this mode, the last 4 bits of the command define the number of bytes to write (from 1 to 16) (Command 0b00010000 will send 1 byte). Hydrabus replies 0x01 to the bulk I2C command. After each data byte the Hydrabus returns the ACK 0x00 or NACK 0x01 bit from the slave device.

###Set I2C speed (0b011000xx) This command sets the I2C device speed. The two last bits will select the speed (in kHz) within the following list :

• 0b00 => 50 kHz
• 0b01 => 100 kHz
• 0b10 => 400 kHz
• 0b11 => 1000 kHz

This commands returns 0x01 if successful, 0x00 in case of error.

###Configure I2C peripheral (0b01000x00) This allows to set the following parameters :

• x sets the pull-up resistors (if 1 use internal on-board pull-up resistors about 50Kohm else use external on-board pull-up resistors)

See https://github.com/bvernoux/hydrafw/wiki/HydraFW-I2C-guide for explanation.

This commands returns 0x01 if successful, 0x00 in case of error.

##Example script The following python script can be used to read 4096 bytes from an I2C EEPROM :

import hexdump
import serial
import struct

#Open serial port
ser = serial.Serial('/dev/ttyACM0', 115200)

#Open binary mode
for i in xrange(20):
    ser.write("\x00")
if "BBIO1" not in ser.read(5):
    print "Could not get into binary mode"
    quit()

# Switching to I2C mode
ser.write('\x02')
if "I2C1" not in ser.read(4):
    print "Cannot set I2C mode"
    quit()

# Reading information
while (addr < 4096*size):
#Write-then-read. 4 bytes to write, 4096 bytes to read 
ser.write('\x08\x00\x04\x10\x00')
#Read command(\x03) and starting address (\x00\x00\x00)
ser.write('\x03\x00\x00\x00')
#Hydrabus will send \x01 in case of success...
ser.read(1)
#...followed by 4096 read bytes
buff += ser.read(4096)

print hexdump.hexdump(buff)

#Return to main binary mode
ser.write('\x00')
#reset to console mode
ser.write('\x0F\n')