Checkout the [linux] or [freebsd] branch.
Userland driver for an MCP4728 Quad DAC attached to the I2C bus of a Gumstix Duovero running FreeBSD.
I was testing with this eval board
I'm using /dev/iic1 since that is the I2C bus brought out on the
Duovero Parlor expansion board header.
I have the I2C bus running at 400 kHz.
The files mcp4728-qdac.c and mcp4728-qdac.h are for incorporation
into a larger program.
The CLI qdac.c is intended only for testing mcp4728-qdac.c.
root@duovero:~# ./qdac -h
Usage: ./qdac [-rweh][<ch> [<val>]]
<none> Dump the output of all input and eeprom registers
-r <ch> Read register for channel, <ch> range 0-3
-w <ch> <val> Write register for channel, <ch> range 0-3, <val> range 0-4095
Note: A value of zero will also disable that channel
-e Use with -r or -w. Works on the eeprom reg instead of the input reg
-h Show this help
The DAC has input and eeprom registers. Operation happens from the input
registers. The eeprom registers are used to populate the input registers at
startup.
Run qdac with no arguments to see the status of all input and eeprom
regs.
root@duovero:~/qdac # ./qdac
input[0]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
eeprom[0]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
input[1]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
eeprom[1]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
input[2]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
eeprom[2]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
input[3]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
eeprom[3]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
Write to an input register
root@duovero:~/qdac # ./qdac -w 2 2048
root@duovero:~/qdac # ./qdac
input[0]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
eeprom[0]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
input[1]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
eeprom[1]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
input[2]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 0 gain: 0 data: 2048
eeprom[2]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
input[3]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
eeprom[3]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
Read just the data for a single input register
root@duovero:~/qdac # ./qdac -r 2
2048
Write to both the input and eeprom register
root@duovero:~/qdac # ./qdac -w -e 0 3333
root@duovero:~/qdac # ./qdac
input[0]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 0 gain: 0 data: 3333
eeprom[0]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 0 gain: 0 data: 3333
input[1]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
eeprom[1]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
input[2]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 0 gain: 0 data: 2048
eeprom[2]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
input[3]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0
eeprom[3]: rdy: 1 por: 1 addr: 0 vref: 0 pd: 3 gain: 0 data: 0