Hiya!
I'm trying to establish comms through an isolated RS232 port to an 89C51RD2 processor, and am having problems.
I've checked the port using a terminal program, and it works happily in loopback up to 28800 kbps. With the processor attached, I can send and receive an uppercase "U" - a scope confirms the baud rate and the reception and transmission of the character.
However, Flashmagic does not seem to want to connect. I've tried different baud rates, communication settings, cable configurations, and nothing seems to work. I cannot read security bits, device IDs, etc. From startup FM has problems. I can, however, clearly see communication taking place on the processor TX/RX lines and at the serial port I/O.
Is there any way to confirm that the processor is in bootROM mode?
Processor oscillator is running at 20 MHz, supply is +5V, PSEN held low on reset.
