Programming Pro Mini with Logic Level Converter and Mega

Development Tools IDE 1.x
1

I have a 3.3v/8Mhz Arduino Pro Mini, an Arduino Mega 2560 R3, and an Adafruit Logic Level Converter. I'm trying to program the Pro Mini with the Mega, but the IDE just sits and does nothing when it gets to the upload part. I've only tried the Blink sketch so far.

I have it currently set up as so:

Mega LLC HV side
GND GND
-- B4
-- B3
TX0 B2
RX0 B1
5V HV
LLC LV side Pro Mini
GND GND
A4 --
A3 --
A2 RXI
A1 TXO
LV VCC
Mega Pro Mini
5V RAW

I tried swapping the RX/TX on one side to no avail. I also tried puting the reset pin from either side through the LLC as well as grounding the Mega's reset pin (without the LCC that time), but that didn't work either. I made sure that the IDE was set to the Mega's USB serial port, a Pro Mini, and the 3.3v/8Mhz ATmega328.

I chose the 3.3v Pro Mini because I will be hooking up 3.3v componenets only. Also, using my already purchased Mega is cheaper than a dedicated 3.3v FTDI. I saw that you can do this several places online, but it isn't working for me.

Any help is appreciated.

2

Swap the RX and TX so you have TX on the mega connected to TX on the Pro Mini, and RX on the mega connected to RX on the Pro Mini.

On the Mega install a jumper between GND and Reset so the Mega main processor will be disabled and not try to do anything with the serial port.
Hold down Pro Mini reset button until the IDE changes from compiling to uploading, then release it. Try a few times if you don't get the timing right.

It is also OK to power the Pro Mini at 5V through the VCC pin and skip the level converter for programming, if you don't have other devices hooked up to the Pro Mini.

3

Hey that did it! Thank you so much. I didn't know that I wouldn't need the Level Converter. I will have other 3.3v device plugged in later, so it's still good that I have it.