Difference between revisions of "MCP4912"
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| − | To set the dac value : | + | To set the dac A value to 2.48V (max range) : |
<pre class="apf"> | <pre class="apf"> | ||
| − | # | + | # echo 1023 > out0_raw |
| − | + | </pre> | |
| + | |||
| + | To set the dac B value to 1V : | ||
| + | <pre class="apf"> | ||
| + | # echo 412 > out1_raw | ||
</pre> | </pre> | ||
Revision as of 15:07, 26 April 2011
Contents
Description
This 2 channels 10bits SPI DAC (Digital to Analog Converter) is mounted in standard on the APF51Dev development boards.
Connections
On your Devlight/DevFull there are 3 signals to use the Max5821:
- DAC_OUTA: corresponds to OUTA (pin 1 of J5 on the APF51Dev). It's the first output.
- DAC_OUTB: corresponds to OUTB (pin 10 of J5 on the APF51Dev). It's the 2nd output.
The default output voltage range is 0->2.5V on the APF51Dev because the reference output of the AS1531 is used as reference for the mcp4912
Driver
The driver is included in ARMadeus distribution, then to use it, select it :
[ ] $ make linux26-menuconfig
Device Drivers --->
<*> Staging drivers --->
<*> Industrial I/O support --->
<M> Microchip MCP4902, MCP4912, MCP4922 driver
Then compile the distribution :
[ ] $ make linux26;make
Use it
modprobe
To use the DAC first load module:
# modprobe mcp49x2
set values
# cd /sys/bus/spi/devices/spi0.1/device0 # ls dac_power_mode_0 out0_raw power uevent dac_power_mode_1 out1_raw subsystem
To set the dac A value to 2.48V (max range) :
# echo 1023 > out0_raw
To set the dac B value to 1V :
# echo 412 > out1_raw
