Defensive code for Heltec Display (#1296)

Added to Heltec board display code logic to reduce corruption of messages on the display

Two piece of defensive code were added

- Only display messages to the display when operating on Core 1 ( Default Arduino ESP32 CONFIG_ARDUINO_RUNNING_CORE )

- Only display one character/string at a time

In the event of failure, default to Serial output.

PS SSD1306 driver similar issues

ThingPulse/esp8266-oled-ssd1306#326
ThingPulse/esp8266-oled-ssd1306#352

main/ZboardHeltec.ino

@@ -32,7 +32,8 @@
 #if defined(ZboardHELTEC)
 # include "ArduinoLog.h"
 # include "config_HELTEC.h"
-// # include "heltec.h"
+
+SemaphoreHandle_t semaphoreOLEDOperation;
 
 void logToLCD(bool display) {
  display ? Log.begin(LOG_LEVEL_LCD, &Oled) : Log.begin(LOG_LEVEL, &Serial); // Log on LCD following LOG_LEVEL_LCD
@@ -125,6 +126,10 @@ OledSerial::OledSerial(int x) {
 
 void OledSerial::begin() {
  // Heltec.begin(); // User OMG serial support
+
+ semaphoreOLEDOperation = xSemaphoreCreateBinary();
+ xSemaphoreGive(semaphoreOLEDOperation);
+
  display->init();
  display->flipScreenVertically();
  display->setFont(ArialMT_Plain_10);
@@ -157,28 +162,24 @@ void OledSerial::fillScreen(OLEDDISPLAY_COLOR color) {
  display->fillRect(0, 0, OLED_WIDTH, OLED_HEIGHT);
 }
 
-size_t OledSerial::write(uint8_t c) {
- display->clear();
- display->setColor(WHITE);
- display->setFont(ArialMT_Plain_10);
-
- display->write((char)c);
- display->drawLogBuffer(0, 0);
- display->display();
- return 1;
-}
-
 size_t OledSerial::write(const uint8_t* buffer, size_t size) {
- display->clear();
- display->setColor(WHITE);
- display->setFont(ArialMT_Plain_10);
- while (size) {
- display->write((char)*buffer++);
- size--;
+ if (xPortGetCoreID() == CONFIG_ARDUINO_RUNNING_CORE) {
+ if (xSemaphoreTake(semaphoreOLEDOperation, pdMS_TO_TICKS(30000)) == pdTRUE) {
+ display->clear();
+ display->setColor(WHITE);
+ display->setFont(ArialMT_Plain_10);
+ while (size) {
+ display->write((char)*buffer++);
+ size--;
+ }
+ display->drawLogBuffer(0, 0);
+ display->display();
+ xSemaphoreGive(semaphoreOLEDOperation);
+ return size;
+ }
  }
- display->drawLogBuffer(0, 0);
- display->display();
- return size;
+ // Default to Serial output if the display is not available
+ return Serial.write(buffer, size);
 }
 
 /*

main/config_HELTEC.h

@@ -87,7 +87,12 @@ class OledSerial : public Stream {
 
  void fillScreen(OLEDDISPLAY_COLOR); // fillScreen display and set color
 
- size_t write(uint8_t);
+ // This is a bit of lazy programmer simplifacation for the semapore and core detecting code. Not sure if it is truly space efficient.
+
+ inline size_t write(uint8_t x) {
+ return write(&x, 1);
+ }
+
  size_t write(const uint8_t* buffer, size_t size);
  inline size_t write(const char* buffer, size_t size) {
  return write((uint8_t*)buffer, size);