Fix MICS6814 heater enable, improve demo

drivers/ioexpander/ioexpander.hpp

@@ -38,6 +38,7 @@ namespace pimoroni {
     static const uint8_t PIN_IN_PULL_UP = PIN_MODE_PU;  // 0b10000
     static const uint8_t PIN_IN_PU = PIN_MODE_PU;       // 0b10000
     static const uint8_t PIN_OUT = PIN_MODE_PP;         // 0b00001
+    static const uint8_t PIN_OD = PIN_MODE_OD;          // 0b00001
     static const uint8_t PIN_PWM = PIN_MODE_PWM;        // 0b00101
     static const uint8_t PIN_ADC = PIN_MODE_ADC;        // 0b01010
 

examples/breakout_mics6814/demo.cpp

@@ -1,21 +1,25 @@
 #include "pico/stdlib.h"
+#include "stdio.h"
 
 #include "breakout_mics6814.hpp"
 
 using namespace pimoroni;
 
-BreakoutMICS6814 ioe;
+BreakoutMICS6814 mics6814;
 
 int main() {
+  stdio_init_all();
+
   gpio_init(PICO_DEFAULT_LED_PIN);
   gpio_set_dir(PICO_DEFAULT_LED_PIN, GPIO_OUT);
 
-  ioe.init();
+  mics6814.init();
+  mics6814.set_heater(true);
+  mics6814.set_led(0, 0, 255);
 
   while(true) {
-    gpio_put(PICO_DEFAULT_LED_PIN, true);
-    sleep_ms(1000);
-    gpio_put(PICO_DEFAULT_LED_PIN, false);
+    BreakoutMICS6814::Reading reading = mics6814.read_all();
+    printf("OX: %f Red: %f NH3: %f\n", reading.oxidising, reading.reducing, reading.nh3);
     sleep_ms(1000);
   }
 

libraries/breakout_mics6814/breakout_mics6814.cpp

@@ -12,7 +12,7 @@ namespace pimoroni {
       ioe.set_mode(MICS_NH3, IOExpander::PIN_ADC);
       ioe.set_mode(MICS_OX, IOExpander::PIN_ADC);
 
-      ioe.set_mode(MICS_HEATER_EN, IOExpander::PIN_OUT);
+      ioe.set_mode(MICS_HEATER_EN, IOExpander::PIN_OD);
       ioe.output(MICS_HEATER_EN, IOExpander::LOW);
 
       // Calculate a period large enough to get 0-255 steps at the desired brightness