Booting the PPDS through Comports

The PPDS was designed to boot after reset from EPROM. The PPDS IIOF pins are set to II0F(3,2,1,0) = (1,1,0,1) after HW reset. For comport boot loading those pins would have to be set to IIOF(3,2,1,0) = (1,1,1,1).

If you MUST boot from comport you have 2 options:

I) After the PPDS boots from EPROM, change the IIOF pins to IIOF(3,2,1,0) =(1,1,1,1), that implies comport booting. If at that point you modify the PC (program counter) to the beginning of the boot loader code, the C4x will attempt to boot from comport.

How do you change the PC value ?
---> invoke the emulator and type a "reset" command in the command window.

Summarizing:

• Step 1. Perform a HW reset (toggle the reset switch)
• Step 2. Invoke the emulator for each C4x that you want to boot load from comport
• Step 3. Perform a SW reset("reset" command in the emulator window)
• Step 4. Leave the processors running free ("RUNF" command)

Notice that this is forcing the comport bootload process. It doesn't reflect the normal conditions after reset.

II) Another option that you have is to modify the board. We don't encourage you to do that, but if you MUST do it, you may lift pin 2 of UK19 (see schematics in PPDS UG page B-7)