16F616 PWM stopped

[jjude]

Code "input_c();" stopped PWM?!?
PWM run on, but when I write code "input_c();"
then PWM not run!
Why?
(PWM output in C5, compiler PCWH 4.099)

[Ttelmah]

TRIS.

You are using standard_io mode (the default). In this mode, the compiler automatically sets the TRIS register according to what you ask. You are asking the compiler to _read_ the whole of port C. Hence it sets TRIS so that the whole port is an input - al bits '1'.

If you look in the data sheet for the PWM, you will find a line like:
"In Pulse Width Modulation (PWM) mode, the CCP1 pin
produces up to a 10-bit resolution PWM output. Since
the CCP1 pin is multiplexed with the PORTB data latch,
the TRISB<x> bit must be cleared to make the CCP1
pin an output."

So the TRIS bit for the PWM output, needs to be a '0' for the PWM to work, and this is being overriden by trying to read the whole port.

Multiple routes round this:
1) Use Fast_io, or fixed_io modes. These put the responsibility onto _you_ to setup the TRIS correctly, but once done, the TRIS setting won't be overriden by reading the port.
2) Don't use the input_c function, but read the port directly. So something like: