Difference between revisions of "MCP4912"
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| − | =Description= | + | ==Description== |
| − | This 2 channels 10bits [[SPI]] DAC (Digital to Analog Converter) is mounted | + | This 2 channels 10bits [[SPI]] DAC (Digital to Analog Converter) is mounted on the [[APF51Dev]] development boards. |
==Connections== | ==Connections== | ||
On your [[APF51Dev]] there are 2 signals to use: | On your [[APF51Dev]] there are 2 signals to use: | ||
| − | * DAC_OUTA: corresponds to OUTA (pin 1 of J5 on the APF51Dev). It's the first output. | + | * 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. | + | * DAC_OUTB: corresponds to OUTB (pin 10 of J5 on the [[APF51Dev]]). It's the 2nd output. |
| − | The default output voltage range is 0- | + | The default output voltage range is [0-2.5V] on the [[APF51Dev]] (because the 2,5V reference output of the [[AS1531]] is used as reference input for the MCP4912). |
== Driver == | == Driver == | ||
| − | The driver is included in ARMadeus distribution, and has to be selected (done by default on [[APF51]]): | + | The driver is included in the ARMadeus distribution, and has to be selected (done by default on [[APF51]]): |
<pre class="host"> | <pre class="host"> | ||
| Line 30: | Line 30: | ||
== Use it == | == Use it == | ||
| − | === | + | === Load driver === |
To use the DAC first load module: | To use the DAC first load module: | ||
| Line 37: | Line 37: | ||
</pre> | </pre> | ||
| − | === | + | === Set channel values === |
<pre class="apf"> | <pre class="apf"> | ||
# cd /sys/bus/spi/devices/spi0.1/device0 | # cd /sys/bus/spi/devices/spi0.1/device0 | ||
| Line 45: | Line 45: | ||
</pre> | </pre> | ||
| − | To set the | + | To set the DAC A channel value to 2.48V (max range) : |
<pre class="apf"> | <pre class="apf"> | ||
# echo 1023 > out0_raw | # echo 1023 > out0_raw | ||
</pre> | </pre> | ||
| − | To set the | + | To set the DAC B channel value to 1V : |
<pre class="apf"> | <pre class="apf"> | ||
# echo 412 > out1_raw | # echo 412 > out1_raw | ||
Revision as of 22:01, 6 October 2011
Contents
Description
This 2 channels 10bits SPI DAC (Digital to Analog Converter) is mounted on the APF51Dev development boards.
Connections
On your APF51Dev there are 2 signals to use:
- 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 2,5V reference output of the AS1531 is used as reference input for the MCP4912).
Driver
The driver is included in the ARMadeus distribution, and has to be selected (done by default on APF51):
[ ] $ 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
Load driver
To use the DAC first load module:
# modprobe mcp49x2
Set channel 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 channel value to 2.48V (max range) :
# echo 1023 > out0_raw
To set the DAC B channel value to 1V :
# echo 412 > out1_raw
