Welcome to the Lounge

#include <Arduino.h>

#include <tft_io.hpp>
using namespace arduino;

using bus_t = tft_spi_ex<VSPI, 5, 23, 19, 18, SPI_MODE0>;

void sendx(uint8_t x, uint8_t value) {
    bus_t::cs_low();
    bus_t::begin_transaction();
    bus_t::begin_write();
    bus_t::write_raw8(x);
    bus_t::write_raw8(value);
    bus_t::end_transaction();
    bus_t::end_write();
    bus_t::cs_high();
}
uint8_t recvx(uint8_t x) {
    bus_t::cs_low();
    bus_t::begin_transaction();
    bus_t::begin_write();
    bus_t::write_raw8(x);
    bus_t::end_write();
    bus_t::begin_read();
    uint8_t result = bus_t::read_raw8();
    bus_t::end_read();
    bus_t::end_transaction();
    bus_t::cs_high();
    return result;
}
inline void send_command(uint8_t value) {
    static const uint8_t RA8875_CMDWRITE = 0x80;
    sendx(RA8875_CMDWRITE, value);
}
inline void send_data(uint8_t value) {
    static const uint8_t RA8875_DATAWRITE = 0x00;
    sendx(RA8875_DATAWRITE, value);
}
inline uint8_t recv_data() {
    static const uint8_t RA8875_DATAREAD = 0x40;
    return recvx(RA8875_DATAREAD);
}
inline uint8_t recv_command() {
    static const uint8_t RA8875_CMDREAD = 0xC0;
    return recvx(RA8875_CMDREAD);
}
uint8_t reg(uint8_t reg) {
    send_command(reg);
    return recv_data();
}
void setup() {
    Serial.begin(115200);
    pinMode(4, OUTPUT);
    digitalWrite(15, LOW);
    delay(100);
    digitalWrite(15, HIGH);
    delay(100);
    bus_t::initialize();
    bus_t::set_speed_multiplier(1/20.0);
    bus_t::begin_initialization();
    uint8_t result = reg(0);
    Serial.println(result);
    bus_t::end_initialization();
    bus_t::set_speed_multiplier(1);
}