I guess, you would want to show a schematic supplementing your nice photo, to get an answer to your question.
PEN is a programming enable pin for the SPI Serial Programming mode, and is internally pulled high.
By holding this pin low during a Power-on Reset, the device will enter the SPI Serial Programming mode. PEN has no function during normal operation.
Apparently all common programmers are working fine without using PEN, it's also not connected in the standard Atmel ISP connector. The internal pull-up resistor is specified in the datasheet, it should be sufficient for an unconnected pin. For nRESET, I suggested an external pull-up (because everyone uses it). I think, it's advisable, if longer traces are connected to the pin, but in the present design, it's not strictly required.As an alternative to using the RESET signal, PEN can be held low during Power-on Reset while SCK is set to “0”. In this case, only the PEN value at Power-on Reset is important. If the programmer cannot guarantee that SCK is held low during power-up, the PEN method cannot be used. The device must be powered down in order to commence normal operation when using this method.
Did you program the specific chip before or is this the first time?
Have you tried the programmer before or with another chip to verify its operation?
What is the value or resistor R21 connected from the sck to the base of the transistor, is it 100 ohm like R19?
Have you checked the soldering of 128 for any shortcircuits (i see some fat solder joints but i don't know if it is just the photo) or have you used any liquid soldiering paste that needs to be cleaned?
Alex
---------- Post added at 15:35 ---------- Previous post was at 15:24 ----------
Why are you using such a low resistor to drive the base of the transistor (even if it is only for T2), you will have a current of about 40ma for each transistor and if the other resistors are the same you will have a problem.
What are the current requirements for the md outputs?
I think a resistor of 1K should be more than enough to drive the base of the transistors.
Alex
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