PIC board working again

The PIC16F887A chips arrived yesterday.

I had to change some things as this chip is the A version. The broken chip is not an A version. After changing those settings the board worked again. Unfortunately this new chip does not solve the programming errors I sometimes get when using the Winpic programing software. Anyway I can continue working on the digital board.

I have changed the port for the switch. I try to use a port for either input or output. I don't want to mix input and output. In the previous configuration It was mixed. That may have destroyed the PIC.

Dependig on the switch setting I can change the center frequency or the frequency span. For each span setting a different sweep frequency must be used.
I use the PWM output to generate this sweep signal. I managed to make this frequency controllable. It now changes when the span setting changes.I am not satisfied yet. I can see the sweep signal make small jumps when a low sweep frequency is used. I want it to be smooth. I will adapt the software improve this behaviour.

Currently the software delays each output increase. this delay is adjustable. Effect is that the sample rate depends on this delay. So for low frequencies the lowpasfilter is not sufficient. I don't want switchable filters as it would require additional hardware. So I will try the approach used by a DDS. I will increase the output of the DAC starting at 0 to max using an adjustable stepsize. That way the sample rate will be fixed. Tonight I will try to implement this.