Difference between revisions of "ADC overo 2.6.39+"

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==Using the ADC's==
 
==Using the ADC's==
 
From posts in the mailing list by Steve Sakoman and others
 
From posts in the mailing list by Steve Sakoman and others
 +
 +
In linux-omap3-2.6.39 and 3.0 and above
  
 
The madc driver is now upstream and in the process it moved to the hwmon subsystem.
 
The madc driver is now upstream and in the process it moved to the hwmon subsystem.
 
It is now even easier to access using the /sys/class interface:
 
It is now even easier to access using the /sys/class interface:
  
−
root@omap3-multi:~# ls /sys/class/hwmon/hwmon1/device/
+
root@omap3-multi:~# ls /sys/class/hwmon/hwmon1/device/
 +
curr10_input  in11_input  in3_input  in7_input    power
 +
driver          in12_input  in4_input  in8_input    subsystem
 +
hwmon          in15_input  in5_input  in9_input    temp1_input
 +
in0_input    in2_input  in6_input  modalias    uevent
  
−
curr10_input  in11_input  in3_input  in7_input    power
+
 
−
driver          in12_input in4_input  in8_input    subsystem
+
  root@omap3-multi:~# cat /sys/class/hwmon/hwmon1/device/temp1_input
−
hwmon          in15_input  in5_input  in9_input    temp1_input
+
56
−
in0_input    in2_input  in6_input  modalias    uevent
+
 
−
root@omap3-multi:~# cat /sys/class/hwmon/hwmon1/device/temp1_input
+
root@omap3-multi:~# cat /sys/class/hwmon/hwmon1/device/curr10_input
−
56
+
-750
−
root@omap3-multi:~# cat /sys/class/hwmon/hwmon1/device/curr10_input
+
−
-750
+
  
 
==ADC's via a system call==
 
==ADC's via a system call==
Line 24: Line 28:
  
 
os.system("cat /sys/class/hwmon/hwmon1/device/in7_input")
 
os.system("cat /sys/class/hwmon/hwmon1/device/in7_input")
−
 
−
==ADC's via sysfs in code==
 
  
 
=== Python ===
 
=== Python ===
−
import os
+
import os
−
 
+
import sys
−
import sys
+
import subprocess
−
 
+
cmd1 = "cat /sys/class/hwmon/hwmon1/device/in7_input"
−
import subprocess
+
process = subprocess.Popen(cmd1, stdout=subprocess.PIPE , shell=True)
−
 
+
os.waitpid(process.pid, 0)[1]
−
cmd1 = "cat /sys/class/hwmon/hwmon1/device/in7_input"
+
udata = process.stdout.read().strip()
−
 
+
print udata     
−
process = subprocess.Popen(cmd1, stdout=subprocess.PIPE , shell=True)
+
−
 
+
−
os.waitpid(process.pid, 0)[1]
+
−
 
+
−
udata = process.stdout.read().strip()
+
−
 
+
−
print udata     
+
  
 
'''In console (in interactive mode)'''
 
'''In console (in interactive mode)'''
  
−
python
+
python
−
 
+
Python 2.6.6 (r266:84292, Sep  1 2011, 13:08:10)
−
Python 2.6.6 (r266:84292, Sep  1 2011, 13:08:10)
+
[GCC 4.3.3] on linux2
−
 
+
>>> import os
−
[GCC 4.3.3] on linux2
+
>>> import sys
−
 
+
>>> import subprocess
−
>>> import os
+
>>> cmd1 = "cat /sys/class/hwmon/hwmon1/device/in7_input"
−
 
+
>>> process = subprocess.Popen(cmd1, stdout=subprocess.PIPE , shell=True)
−
>>> import sys
+
>>> os.waitpid(process.pid, 0)[1]
−
 
+
0
−
>>> import subprocess
+
>>> udata = process.stdout.read().strip()
−
 
+
>>> print udata
−
>>> cmd1 = "cat /sys/class/hwmon/hwmon1/device/in7_input"
+
1388
−
 
+
>>>
−
>>> process = subprocess.Popen(cmd1, stdout=subprocess.PIPE , shell=True)
+
−
 
+
−
>>> os.waitpid(process.pid, 0)[1]
+
−
 
+
  
−
==
+
==Using sysfs from c and fopen and fread==
 +
A much useful way to access the adc's is using fopen and fread.
  
 +
#include <stdio.h>
 +
#include <stdlib.h>
 +
#include <string.h>
 +
FILE *fp;
 +
int main(void)
 +
{
 +
    char read_value[4];
 +
    char adcVal2[6];
 +
    if (( fp = fopen("/sys/class/hwmon/hwmon1/device/in2_input", "r")) == NULL)
 +
    {
 +
        printf("Can not open hwmon1 \n");
 +
        exit(1);
 +
    }
 +
    rewind(fp);
 +
    fread(&read_value, sizeof(char), 1 , fp);
 +
    strcpy(adcVal2 , read_value);
 +
    fclose(fp);
 +
    printf("\nADC 2 value = %s \n",adcVal2);
 +
    return 0;
 +
}
  
 
==Building your own kernel ==
 
==Building your own kernel ==

Latest revision as of 23:11, 20 September 2011

Using the ADC's

From posts in the mailing list by Steve Sakoman and others

In linux-omap3-2.6.39 and 3.0 and above

The madc driver is now upstream and in the process it moved to the hwmon subsystem. It is now even easier to access using the /sys/class interface: 

root@omap3-multi:~# ls /sys/class/hwmon/hwmon1/device/
curr10_input  in11_input  in3_input  in7_input    power
driver          in12_input  in4_input  in8_input    subsystem
hwmon          in15_input  in5_input  in9_input    temp1_input
in0_input     in2_input   in6_input  modalias    uevent



root@omap3-multi:~# cat /sys/class/hwmon/hwmon1/device/temp1_input
56

root@omap3-multi:~# cat /sys/class/hwmon/hwmon1/device/curr10_input
-750

ADC's via a system call

a quick and very nasty way to access them is by a system call

C

system("cat /sys/class/hwmon/hwmon1/device/in7_input");

Python

os.system("cat /sys/class/hwmon/hwmon1/device/in7_input")

Python

import os
import sys
import subprocess
cmd1 = "cat /sys/class/hwmon/hwmon1/device/in7_input"
process = subprocess.Popen(cmd1, stdout=subprocess.PIPE , shell=True)
os.waitpid(process.pid, 0)[1]
udata = process.stdout.read().strip()
print udata

In console (in interactive mode) 

python
Python 2.6.6 (r266:84292, Sep  1 2011, 13:08:10)
[GCC 4.3.3] on linux2
>>> import os
>>> import sys
>>> import subprocess
>>> cmd1 = "cat /sys/class/hwmon/hwmon1/device/in7_input"
>>> process = subprocess.Popen(cmd1, stdout=subprocess.PIPE , shell=True)
>>> os.waitpid(process.pid, 0)[1]
0
>>> udata = process.stdout.read().strip()
>>> print udata
1388
>>>

Using sysfs from c and fopen and fread

A much useful way to access the adc's is using fopen and fread. 

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
FILE *fp;
int main(void)
{
   char read_value[4];
   char adcVal2[6];
   if (( fp = fopen("/sys/class/hwmon/hwmon1/device/in2_input", "r")) == NULL)
   {
       printf("Can not open hwmon1 \n");
       exit(1);
   }
   rewind(fp);
   fread(&read_value, sizeof(char), 1 , fp);
   strcpy(adcVal2 , read_value);
   fclose(fp);
   printf("\nADC 2 value = %s \n",adcVal2);
   return 0;
}

Building your own kernel

When building your own kernel Make sure your defconfig has CONFIG_TWL4030_MADC and CONFIG_SENSORS_TWL4030_MADC and make sure your rootfs has the module.

Link to kernel docs for Kernel driver twl4030-madc http://www.sakoman.com/cgi-bin/gitweb.cgi?p=linux-omap-2.6.git;a=blob;f=Documentation/hwmon/twl4030-madc-hwmon;h=ef7984317cecb29eca6ef23a30c21d920e66ef31;hb=refs/heads/omap-2.6.39-pm

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