In fact the Pcb is done simply for the moment to get used to the MCP23017 that will serve me to something else after.

The PCB is composed of 8 LED simply placed on Port A and 8 LED placed on port B. The communication with the Pic I2C is done.
Pic also controls an LCD 2 * 16.

The test program is to enable a counter from 1 to 255 that will be displayed on the LCD (i = 1 until i = 255) and the 2 * 8LED (port A and port B).

At the first power, while port A is activated (LED lit) and port B is disabled (LED off). When the counter reaches + / - 130 (viewed from the LCD), Port A (which was fully activated) starts from the port B but it does not change state. And only when the counter recomm early as 2 port (A and B) fonctionnnent normally (they have at the same time as the LCD).
And it works very well.
The problem is powering up.

The problem must come from the Start Bit of the I2C.
I already tried some codes for the Start bit but I can not.

Aurra you an idea?


Again thank you for your reply

Claudy