Serial port AVR programmer

December 3, 2009
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I’m still testing the newest USBmicro firmware. Meanwhile I thought I would document a little serial port to AVR programmer I made. The design is from a schematic on the Internet. Obviously the design was by Olimex. Note that the simple programmers of this type only work with a laptop or PC with a “real” serial port – a USB-to-serial does not work.

This is the schematic. Ignore the 10-pin header on the right. You will want to replace it with the 6 pin header.

sch

This is the top of the board:

serprog1

These are the parts:

parts

These are the part locations:

serprog3

Yellow arrow – R1
Green arrow – R2
Violet arrow – R4
Red arrow – R5
Blue arrow – R3

Diodes. Note their orientation. The band on the diode has to be in the circuit as shown:

serprog4

Red arrow – Z1
Green arrow – Z2
Yellow arrow – D1

6 pin connector:

serprog5

Green arrow – MISO, Pin 1
White arrow – SCK
Yellow arrow – Reset
Red Arrow – 5V from target
Blue arrow – MOSI
Black arrow – ground

This highlighted path shows all of the ground connections. Note it goes under the transistor base lead:

serprog6

That is a path of solder from pins 6 and 7 of the Dsub-9 connector to R1:

serprog7

The highlighted is the connections to 5V:

serprog8

This shows the base lead going over, but not touching ground, and connecting to R5 and D1:

serprog9

This is pin 1 of the Dsub-9 connector:

serprog10

On the 10 pin connector, pin 1 is MOSI, 5 is Reset, 7 is SCK, 9 is MISO, and 2 is 5V.

They need to be connected differently when connected to the 6 pin connector.

isp

sch

If you copy this exactly, counting holes and placing the components in the very same locations, you should be able to get this circuit working.

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