What is the main difference Bet. 16f877 vs 16f877A

[Joann]

i have run the alive test i didnt work, and what surprise me is when i run another code on the pic it works..
any solution or do i post the source here.

[mister_e]

Sounds weird to me so just post your Whole code AND the according .HEX compiled file to compare.

[paul borgmeier]

Great information (and you are closer to a solution) -
Let me make sure I understand

- The code works on a 16F876 but not a 16F877A
- The alive test does not work on the 16F877a when inserted into your code and the PIC inserted into your circuit
- The same16F877A works when tested with other code in another circuit

If the above is all true, it sure sounds like a hardware / config issue.

What do you have connected to pin 1 of the 877A

Describe your power supply?

Do you have all four Vdd and Vss pins connected?

Do you have decoupling caps between each pair of Vdd and Vss?

What are your config setting?

What are you using for an oscillator?

What registers are you using and how are they set?

If we cannot find the problem with this information, the nest step is to post a schematic and code.

Paul Borgmeier
Salt Lake City, Utah
USA

[Joann]

this is my connection

On porta.0 = clock of 74hc574
On porta.1 = clock of 74hc574
On porta.2 = clock of 74hc574
On porta.3 = cts
On porta.4 = serialin
On porta.5 = serialout

I use three 74hc574
portb.0-7 = pin2 -pin8 of 74hc574
portc.0-7 = pin2 - pin8 of 74hc574

[Joann]

I thank everybody in the forum who contributed to make my effort to become succesful.
the code now is working perfect.
filter caps,and cmcon = 7
adcon1 =7
and configuration,and a little hardware fault,.

[Joann]

How can i read the whole byte on the i2c 24c16?
The code i wrote is this,"i2cread dpin,cpin,$a0,char,[char2disp]"
It only reads the first 256bytes,only, i am using the code to display moving sign display on led matrix.

[mister_e]

Your variables declaration and a snip of your code woud help!