Hi @happy_kass and @paulvha thank you again for your support.
I successfully flashed the ATTiny, now the NFC Reader works.
Some additional info for anyone else coming here:
- I have used an Arduino Nano instead of a Mega (pinouts / cabling below)
- As it is not mentioned in happy_kass solution: there are several board URLs for the ATTiny, but some of them are outdated and throw compile errors. I have used this one: https://drazzy.com/package_drazzy.com_index.json (add URL to Preferences/Additional Board URLs and then download the “ATTinyCore” by Spence Konde via Board Manager), I used version 1.5.2 without issues
- From “Tools/Board” select the “ATTinyCore/ATTiny24/44/84(a) (No Bootloader)”
For Arduino Nano, you need to:
- In ArduinoISP sketch:
- enable #define USE_OLD_STYLE_WIRING
- enable #define SPI_CLOCK (128000/6)
- disable #define SPI_CLOCK (1000000 / 6)
- leave MOSI, MISO, SCK as it is (11, 12, 13)
- connect the Arduino Nano board to the NFC Reader as followed:
nfc reader => mega ; nano
3v3 => 3v3
gnd => gnd
mini pin/miso => mega (cipo/50) ; nano (cipo/d12)
sda/mosi (51) => mega (copi/51) ; nano (copi/d11)
scl => mega (sck/52) ; nano (sck/d13)
rst => mega (ss/d10) ; nano (ss/d10)
happy_kass writes that on the Qwiic board, the mini pin is the “MOSI” pin, but it is the MISO pin.
With “mini pin/miso” I refer to the little special pin left below the “I2C” label. I soldered a tiny cable there.
In addition to a capacitor (I used a 470uF, minus/stripe goes to GND) I have added a 10kOhm resistor between 5V and D10 as described in the posting here ( Arduino Nano ISP Dongle : 5 Steps - Instructables )
