232r to 5v atmega

Hey there,

So I built my own pcb which includes an atmel micro with arduino bootloader. The micro is running on 5v (it is a 5v model), but I have a 232r -3v3 uart. I have attempted to upload code using the arduino developer environment, but with no success. Error code:

"avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

So, data is not getting read by the arduino or received by the pc. Given that its 5v, the threshold should be around 2.5v, so the micro should be able to read the data, but I am concerned about 5v being sent from the micro to the uart (perhaps this is where the issue lies). Does anybody have any ideas?



Hi. What do you mean when you say its a -3v3 type? I thought that rs323 specified about -15 - 15 volts. I have used a max232 and a max232 (which doesn't need external capacitors) with an 8051 micro (which is also 5v) and it worked perfectly. Also, if you are worried about 5 volts being too high, could you perhaps use a voltage divider to get it down to 3?

Good luck.

What are you doing about the auto reset on the DTR line, is this in place or are you doing a manual reset when you upload your code?