Attached is what I have done to mine.
Not pretty, but it works if you have a USB UART 5V breakout
My programming header is on the bottom of the PCB.
1. Add 10K pull-up to 5V on reset/pin 1 uC.
2. Add a 0.01uF cap from reset/pin 1 to ground.
3. Add a 0.1uF cap from reset/pin 1 to pin 1 on a 4 pin header
(I used a 5 pin header to solder it to the ground plane on both
4. Add a wire from pin 2 on the uC to pin 2 on the 4 pin header
5. Add a wire from pin 3 on the uC to pin 3 on the 4 pin header
6. Connect ground to pin 4 on the 4 pin header
7. DO NOT cut a trace and cover it with a header before noticing
unless you want to be confused for a bit.
It's important to get the relative cap sizes right on the reset
On 3/22/2018 11:29 AM, Trevor Jacobs via Groups.Io wrote:
I got a request to draw up the schematic of the
programmer I put together, so I thought I'd share it
with the rest of the group in case anyone was wanting
to program their Soda Pop or Slop Bucket. Had a little time this afternoon, so drew
it up. If you have any questions, please feel free
to email me. I used the MAX3232 instead of the
typical MAX232 (same pinouts though) because it
requires only .1 uF caps vs. 10uF caps of the
MAX232. I use this with a cheap USB to RS232
adapter on my computer and it works FB. You could
also get one of the FTDI USB232 (FT232RL) cards
off of ebay and connect it similarly - no level
conversion (MAX232) needed as it's logic level.
Just make sure that you get a card that brings out
the DTR line. Many of them only bring out the CTS
and RTS lines but the DTR is needed for the RESET
line if you want to use it as a programmer. Keep
in mind that this dongle does not program the
bootloader into the chip. For that you need a
different device that uses the SPI port (MOSI,MISO
etc.) or you can make a burner out of an Arduino
Nano or Arduino Uno. Hope this helps!
73 es God bless de Trev K6ESE