I have an embedded device that uses RS-232 to communicate with a PC. We recently switched over to using the TRS232E from the Maxim MAX232 chip. I noticed that if I connect the device to a teminial program, open the port and then switch the device on I see upto 20 bytes of garbage come though (at 115200 baud). When looking at the TX pin on my O'scope I can see that when the device is switched on the TX pin goes high (to about 10V) for around 100 ms and then it goes low (to about -10V) and stays there until data is transmitted. If I take out the TRS chip and insert an old MAX232 and switch on the device the TX pin does not go high, it just goes from zero to -10V. Normally this wouldn't be a huge problem but my device has bootloader functionality and the garbage data causes the bootload process to fail sometimes. Any ideas why this is occurring or how to make it stop? I am using 1.0uF ceramic caps for all the capacitors.
-
Ask a related question
What is a related question?A related question is a question created from another question. When the related question is created, it will be automatically linked to the original question.
