Hardware:
Due
Adafruit 7-segment Feather
driving 3 x 2.3" 7-Segment Displays (Feather only drives 1 led segments ... the 2.3" Segments have 4 leds in series ... extra circuitry has been added to provide this functionality)
At Issue:
can't get seem to get the DUE to communicate with the feather
was expecting to use the DUE SDA(1) & SCL(1) (pins 70 & 71) to drive the Feather SDA SCL
Feather has 10K pullups to VDD (5V) on both lines connected directly to a HT16K33 ... the DUE has no pullups on SDA(1) or SCL(1) ... concerned with 3v3/5V warnings, added a level converter between the 2 devices (Due SDA(1) & SCL(1)) 10K to 3V3, S-2N7000, G-2N7000 (3V3), D-2N7000 (Feather SDA & SCL)
Testing:
#include <Adafruit_GFX.h>
#include <Adafruit_LEDBackpack.h>
float dRdng;
Adafruit_7segment dsp = Adafruit_7segment();
Serial.begin(9600);
loop() {
dRdng = readADC(0); // A0 reading
dsp.print(dRdng);
dsp.writeDisplay();
Serial.println(dRdng);
delay(1000);
}
10k resistors externally pulled up to 3.3V on SDA(1) & SCL(1) (pins 70 & 71)
1k5 resistors internally pulled up to 3.3V on SDA & SCL (pins 20 & 21)
using a 200MHz Digital Scope I see no activity on any of these 4 pins ... was expecting to see data every second
Online there are a number of threads going back several years suggesting there are issues with the DUE I2C ... some suggesting there was a fix in around board version 1.6.6 ... using board version 1.6.12
already designed & built using this hardware so hoping to find a solution before the new year