hobbss
Member level 2
So I found out the hard way that the ATMEGA1281 does not use the SPI pins for ISP (what's that pnemonic about how to spell "assume"?).
I have a second design that I am ready to send to the board house, but would like to confirm that I actually have the ISP pins identified correctly. I am using a AVRISP mkii programmer (6 pin)
As I [now] understand it, the connections should be:
Furthermore, because I also have an RS-232 transceiver on these pins, I think I need a series resistor on those two lines, between the transceiver and where the ISP connector ties in
I have attached a schematic describing what I mean.
Does anyone have any experience with the ATMEGA1281 ISP pins?
I have a second design that I am ready to send to the board house, but would like to confirm that I actually have the ISP pins identified correctly. I am using a AVRISP mkii programmer (6 pin)
As I [now] understand it, the connections should be:
Code:
ISP Connector ----> ATMEGA
MISO (pin 1) -------- PDO = PE1 on 1281
MOSI (pin 4) -------- PDI = PE0 on 1281
SCK (pin 3) --------- PB1 on 1281
GND, Vcc -- GND, Vcc.
Furthermore, because I also have an RS-232 transceiver on these pins, I think I need a series resistor on those two lines, between the transceiver and where the ISP connector ties in
Code:
MAX232 --- 1kOhm resistor -----+-----PEx
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ISP Signal
I have attached a schematic describing what I mean.
Does anyone have any experience with the ATMEGA1281 ISP pins?