Hiya,

I'm currently working on a small project which involves interfacing a microcontroller via CAN Bus to a large robot.
I'm having problems with using the UART bootloader to flash my firmware.

I've build a small circuit on breadboard which features:
- a selfmade PLCC-DIL adaptor for the T89C51CC02 (it works with Galep-4)
- the simple minimum reset circuit from the data sheet featuring a single small capacitor
- a clock generating circuit using a complete resonating IC (16MHz)
- a MAX232CPE with appropriate capacitors for the RS232 link
- a lone low-current LED as "Hello world" marker on P1.0

For the bootloader condition on P1: P1.1 to P1.7 connected to +5V, P1.0 connected to GND to form FEh on P1.

I programmed the UART bootloader into the chip with a Galep-4 programmer (I bought a T89C51CC02CA piece instead of the ..UA) and as a first test, a single hello world app. I also killed any security bits and made sure that the bootloader condition is set to P1=FEh.

The hello world app worked - so my clock circuit is ok, my basic reset is ok.
Now I hooked up the bootloader condition and tried the serial link. Nothing responded. The Atmel Flip tool gives me timeout for any baudrate although the UART bootloader spec says any baudrate should be valid for a 16Mhz clock. I also tried the "Manual sync" option which didn't help either.
A terminal program gave me no response at all.

The MAX232 has been tested in loopback condition and it worked ok with a terminal program.

I tried loading a brutal launch of the bootloader code into the flash (meaning LJMP 0F800h at 0h) but I still get no response from the bootloader.

Now I'm a bit stuck...I can program the device with the galep-4 but doing it in-system via the RS232 would be a lot nicer.

I'm sure I missed some detail or I did a subtile error in my circuit but for the moment I'm unable to find it.

Any ideas?

cheers,
Matthias