Setting an ADC channel is required to be set before using ADC.
If you do not set this, a channel which has the same index of channel with the ADC device's index will be assigned.
For example, Channel 0 is automatically assigned to ADC 0 as default channel.
You can read ADC values from the channels sequentially by switching among channels.
To set channel or switch to another channel, use the following command:
pid_ioctl($pid, "set ch N"); // set channel
You can get current channel id by using following command:
<?php pid_ioctl($pid, "get ch"); // get the current channel ?>
Parameter N means the number of channel.
<?php $pid = pid_open("/mmap/adc0"); // open ADC 0 pid_ioctl($pid, "set ch 1"); // set channel to 1 pid_ioctl($pid, "set ch 2"); // set channel to 2 echo pid_ioctl($pid, "get ch"); // print the current channel(output: 2) pid_close($pid); // close ADC ?>