Multiple peripherals: 8Bit parallel and SPI

[danielkboyer]

User Setup

// Tell the library to use 8 bit parallel mode (otherwise SPI is assumed)
#define TFT_PARALLEL_8_BIT

// The ESP32 and TFT the pins used for testing are:
#define TFT_CS   33  // Chip select control pin (library pulls permanently low
#define TFT_DC   18  // Data Command control pin - must use a pin in the range 0-31
#define TFT_RST  32  // Reset pin, toggles on startup

#define TFT_WR    4  // Write strobe control pin - must use a pin in the range 0-31
#define TFT_RD    2  // Read strobe control pin
#define TFT_D0   12  // Must use pins in the range 0-31 for the data bus
#define TFT_D1   13  // so a single register write sets/clears all bits.
#define TFT_D2   26  // Pins can be randomly assigned, this does not affect
#define TFT_D3   25  // TFT screen update performance.
#define TFT_D4   21
#define TFT_D5   17
#define TFT_D6   27
#define TFT_D7   14

This is working with my ESP32 and 3.5 inch tft shield.

I added an nfc reader and that works

#define PN532_SCK  (18)
#define PN532_MISO (19)
#define PN532_MOSI (23)
#define PN532_SS   (5)

// Use this line for a breakout with a software SPI connection (recommended):
Adafruit_PN532 nfc(PN532_SCK, PN532_MISO, PN532_MOSI, PN532_SS);

But when I try to use them at the same time the screen wins over the NFC reader.

I tried to write the pins to low and high when writing data but nothing worked.

setup

 pinMode(TFT_CS, OUTPUT);
  
  pinMode(PN532_SS, OUTPUT);
  // We need to 'init' both the nfc reader and display
  // at the same time. so set both cs pins low
  digitalWrite(TFT_CS, LOW);
  digitalWrite(PN532_SS, LOW);

  establishConnection();
  initScreen();
  rfidSetup();

  digitalWrite(TFT_CS, HIGH);
  digitalWrite(PN532_SS, HIGH);

Before I write I set the correct pin to LOW and after writing set it back to HIGH.

In the comments it states "library pulls permanently low", does this mean it's not possible to set the pin to high?

[danielkboyer]

Figured it out... I was using the same pin for Data Command and SCK. For those who are wondering that was pin 18. So I just switched the TFT_DC pin to 22 (which is in the range of 0-31).