Trouble programming 328P chip with FTDI friend

I'm trying to program a 328 chip using an FTDI friend. I have the power and ground hooked up correctly, along with the RX/TX lines to the FTDI friend. I also have a crystal hooked up, and a sketch already loaded (blinking LED) is working fine.

When I go into the Arduino IDE, I'm choosing Demuilanoe, 328 (these chips can pre-bootloaded from Adafruit). However, when I try to upload, I never see any response on the RX on the FTDI, like the chip just isn't responding, and the IDE says that it's not responding....

I have a resistor pulling the reset pin to 5V, however, I don't have a 0.1uF capacitor to hook up between the DTR pin of the FTDI, so I'm just hooking it up directly to the reset pin.

Could that be why it's not entering programming mode (missing that capacitor)? If so, can I use a bigger capacitor? I have 2.2uF and 1000uF's available, but I don't know which way to orient them (+/-)....

Thanks!

Holding RESET high puts it into ICSP programming mode. It should not be high for serial/FTDI programming. It should be under the control of the programmer - that's why we use FTDIs, because they have an extra line for reset.

osmosis311:
Could that be why it's not entering programming mode (missing that capacitor)?

Yes, duhh. If it's designed with a capacitor it's there for a reason. You can try 2,2uF but I'm afraid that's to big.

Alternative, use the pullup for reset and add a switch to ground. Push the switch if you hit compile and release it as soon as the IDE says uploading. (That's normally the moment the FTDI would reset the board.)

Still not working.

One question: if I did have a 0.1uF capacitor, how would I know which way was + and which was -? The reset pin vs the FTDI?

Maybe it's easier to just keep using an Uno as my programmer and popping the chips in and out...

Most 0.1uF caps are not polarized. If you unfortunately have one which is polarized, negative should go to reset.

osmosis311:
Maybe it's easier to just keep using an Uno as my programmer and popping the chips in and out...

Or get yourself Arduino Pro Mini's. They are almost the same price as a single ATmega328 but have the voltage regulator, crystal and caps all on-board :slight_smile: