Wi-Fi won't start after long SPI transfer

[azevedo-manuel]

Basic Infos

Hardware

Hardware: Wemos D1 mini Pro
Core Version: 2.3.0

Description

If sending a long SPI sequence before initializing Wi-Fi, Wi-Fi won't connect anymore. Example bellow fails at 29 times sending data over SPI, but works up to 28 times.
If starting Wi-Fi first, the problem seems to disappear.

Settings in IDE

Module: WeMos D1 R2 & mini
Flash Size: 4MB
CPU Frequency: 80Mhz
Upload Using: SERIAL
Reset Method: nodemcu

Sketch

#include <SPI.h>
#include <ESP8266WiFi.h>

char ssid[] = "myssid";
char pass[] = "mypassword"; 

void setup() {
  Serial.begin(115200);

  Serial.print("setup: Connecting to ");
  Serial.println(ssid);

  startupLogo(); // this makes the SPI calls
  
  WiFi.begin(ssid, pass);

  Serial.print("setup: ");
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println();
  
  Serial.println("setup: WiFi connected");
}

void loop() {

  SPIwrite(D0,0x53122);
  Serial.print("Loop!");
  delay(500);
  
}

void SPIwrite(byte nCS, unsigned long theString) { 
  Serial.printf("SPIwrite: SPI value = 0x%08x ",theString);
  Serial.println(theString,BIN);
  
  SPI.begin();
  SPI.beginTransaction(SPISettings(15000000, MSBFIRST, SPI_MODE0));
  digitalWrite(nCS, LOW); // device select
  SPI.transfer(theString); // 8 bits out
  digitalWrite(nCS, HIGH); // data  transfer to SPI outputs...
  SPI.endTransaction();
  SPI.end();
}

void startupLogo(){
  int i=0;

  while (i<29) {
    SPIwrite(D3, 0x22122);
    i++;
    delay(100);
  }

}