Matrix user forums

Hi.
I'm a newbie trying to get back into programming, and learning about PICs and ARMs in the process.
I have a bunck of E-block boards and have been following through some of the Matrix C course work.
When I plug the EB008 board into Ports A & B and run any of the display or timer programs, for example excercise 4.9 everything works except the 'f' segment of all four LED digits. None of these illuminate. I have checked the display on another port, driving just the left most digit, and the 'f' segment does work.
I have run Test,bin on the ARM board and checked all ports with the EB004 LED board and they all work correctly.
I notice in the EB185-30-01.pdf document under section 4.6 & 4.7 it says the following:
4.6 ARM Test program details
ARM Test program has two stages which are repeated continuously.
1) LEDs on each port light in alternate pairs creating a 1-0-1-0 to 0-1-0-1 pattern. The pattern repeats 5 times
2) The entire port flashes on and off. The pattern is repeated 5 times.
3) Check on each port to see that both the alternating pattern and the flashing pattern are correct. (Excluding B5, D4 and E4-7 – see notes below).
4.7 Important Notes:
• Pins B5 and D4 are used with caution (they are USB pins and using them causes USB issues).
• Port E only uses pins 0-3. Pins 4-7 are analogue only ports which are not used in this test.
• The User test requires the ARM board to have the Matrix OS program loaded onto the

Pin B5 happens to be the pin that drives R6 on the EB008 LED Display board - and R6 happens to drive the 'f' segment of the displays.
Has this got anything to do with my display problem?
And what does it mean in section 4.7 where it says: Pins B5 and D4 are used with caution (they are USB pins and using them causes USB issues).

Thanks for any help.
Zai

Hello Zai

There is a small two way jumper on the board labelled J18. If you move this to the I/O position then the pins B5 and D4 are connected to the E-Block ports. If you have the jumper in the USB position then the pins are connected to the USB circuitry to allow the USB bootloader to work. Therefore you will need the jumper in the USB position to modify the program on the board.

Thanks Ben.
That makes perfect sense of course, and a great help.

Zai

Hi Ben
One more thing for clarification:
4.7 in the EB185 data sheet says: 'Pins B5 and D4 are used with caution (they are USB pins and using them causes USB issues).'
What kind of caution is needed. Is it saying that if you switch JP18 you simply cannot program the chip via USB, or are there other implications - such as damaging those ports?

Regards
Zai