Programming the propeller chip TTL to USB

dr hydra

I'm trying to use an arduino Uno as a TTL to usb device to program the propeller chip and I am having trouble understanding the DTR to reset role on the propeller chip. Is it as simple as putting the Arduino MEGA 328 chip into a reset (jumper wire from GND to Reset). Then connecting the propeller chip to the arduino RX/TX lines…making sure to use a voltage divide on the TX line. The DTR line seems to be available at the ICP1 port 4 on the arduino. Then I would connect that port to the reset of the propeller with 1M pulldown. Would that work? I’m guessing the Arduino would show up as a COM port in the propeller IDE

jmg

dr hydra wrote: »

I’m guessing the Arduino would show up as a COM port in the propeller IDE

that would be the first thing to confirm...
ie Connect a terminal, reset the M328 and check you can
a) Echo bytes with bridged TX-RX
b) Change baud rates to Prop values & check they actually apply.
c) Wiggle DTR

If those pass, it is working as a General USB-UART bridge.

dr hydra

It looks like I was looking at the schematic wrong. The DTR line is tied to the 328 reset, therefore, by shorting to GND (LOW) the DTR will not wiggle. Since the 328 is a DIP…I’m guessing I could just remove the chip from the board and it would become a TTL to USB with TX/RX/and DTR at the reset. Then just replace the 328 when I want to use it as Arduino again

Jeff Haas

Erco sez...Check ebay for cheap USB to TTL adaptors.