Arduino IDE Serial Monitor not working when using SPI device

[UoGTFranklin]

Hi all,

I have an ESP32-WROVER module with an SPI TFT conneted and running as a Websocket host. I have a series of Serial.println() commands within the code so I can track progress and also to output some details such as the url of the Websocket server. Initially this works fine, however after I initialise the TFT none of the Serial.println() commands work and instead I get a backwards question mark showing on the Serial Monitor. I understand that I am essentially using the serial interface of the ESP32 in different ways once the SPI is initialised, however I have seen other code using SPI TFT devices with Serial.println() commands after TFT initialisation. Has anyone come across this problem previously, or is aware of a restriction on using Serial Monitor and SPI interface simultaneously?

Thanks

[Codebox]#include <SPIFFS.h>
#include <SPI.h>

#include <ArduinoWebsockets.h>
#include <WiFi.h>

#include <TJpg_Decoder.h>
#include <TFT_eSPI.h>

const char* ssid = "Galaxy_A405140";
const char* password = "xovh7102";
const char* imageFileName = "/camimage.jpeg";

using namespace websockets;
WebsocketsServer server;
WebsocketsClient client;

TFT_eSPI tft = TFT_eSPI(); // Invoke custom library
boolean SDInited = false;

bool tft_output(int16_t x, int16_t y, uint16_t w, uint16_t h, uint16_t* bitmap)
{
// Stop further decoding as image is running off bottom of screen
if ( y >= tft.height() ) return 0;

// This function will clip the image block rendering automatically at the TFT boundaries
tft.pushImage(x, y, w, h, bitmap);


// Return 1 to decode next block
return 1;
}


void setup() {
// put your setup code here, to run once:
Serial.begin(115200);
while(!Serial);
Serial.println("Test");
delay(1000);

if(!SPIFFS.begin(true)){
Serial.println("SPIFFS init failed!");
while(1) yield();
}else{
SDInited = true;
Serial.println("SPIFFS init success");
}

Serial.println("Beginning WiFi");
//WiFi.begin(ssid, password);
WiFi.begin(ssid, password);
delay(500);

for(int i = 0; i < 15 && WiFi.status() != WL_CONNECTED; i++) {
Serial.print(".");
delay(1000);
}

IPAddress IP = WiFi.localIP();
Serial.print("IP Address : ");
Serial.println(IP);

Serial.println("Beginning TFT");
delay(1000);
tft.begin();
tft.setRotation(3);
tft.fillScreen(random(0xFFFF));
delay(1000);
Serial.flush();
delay(1000);
Serial.println("TFT init success");
//tft.setSwapBytes(true); // We need to swap the colour bytes (endianess)

// The jpeg image can be scaled by a factor of 1, 2, 4, or 8
TJpgDec.setJpgScale(1);

// The decoder must be given the exact name of the rendering function above
TJpgDec.setCallback(tft_output);

//Serial.println(" ");
//Serial.println("Setting AP...");
//WiFi.softAP(ssid, password);

// IPAddress IP = WiFi.localIP();
// //Serial.print("AP IP Address : ");
// Serial.write(IP);

Serial.println("Awaiting images...");
server.listen(80);
}

void loop() {
// put your main code here, to run repeatedly:
if(SDInited){
if(server.poll()){
WebsocketsClient client = server.accept();
}

if(client.available()){
client.poll();

WebsocketsMessage msg = client.readBlocking();
boolean isSaved = fileWrite(imageFileName, msg);
if(isSaved){

uint32_t t = millis();

// Get the width and height in pixels of the jpeg if you wish
uint16_t w = 0, h = 0;
TJpgDec.getFsJpgSize(&w, &h, imageFileName); // Note name preceded with "/"
Serial.print("Width = "); Serial.print(w); Serial.print(", height = "); Serial.println(h);

// Draw the image, top left at 0,0
TJpgDec.drawFsJpg(0, 0, imageFileName);

// How much time did rendering take (ESP8266 80MHz 271ms, 160MHz 157ms, ESP32 SPI 120ms, 8bit parallel 105ms
t = millis() - t;
Serial.print(t); Serial.println(" ms");
}
}
}
}

boolean fileWrite(String name, WebsocketsMessage content){
File file = SPIFFS.open(name.c_str(), "w");
if(!file){
String errorMsg = "Can't open file";
Serial.println(errorMsg);
return false;
}else{
file.write((const uint8_t*) content.c_str(), content.length());
file.close();
return true;
}
}[/Codebox]