Sharp Memory display via SPI from Arduino Nano RP2040 C++ - c

Question

I have an Adafruit Sharp Memory display connected via SPI to Arduino Nano Connect RP2040. I don't use Arduino IDE nor libraries. I write the code in C++ like I would write for RP2040 on Pi Pico, so I'm using Pico/RP2040 libraries. I'm building it and then just copying the .uf2 file to Arduino.
I'm trying to control the display but without success and I have no idea what I'm doing wrong. Here is my code, where I'm sending a command which should clear the display but it does not:
#include <stdio.h>
#include <stdlib.h>
#include "pico/stdlib.h"
#include "hardware/spi.h"
#include "hardware/gpio.h"
// ---SPI
// Pins for Arduino
#define SCK_PIN 13 // SCLK / SCK
#define MOSI_PIN 11 // MOSI / COPI
#define SS_PIN 10 // SS / CS
// ---Sharp display
#define WIDTH 144
#define HEIGHT 168
int main() {
stdio_init_all();
printf("START \n");
bool vcom_bool_{false};
spi_init(spi0, 2000000);
spi_set_format( spi0, 8, SPI_CPOL_0, SPI_CPHA_0, SPI_MSB_FIRST);
gpio_set_function(MOSI_PIN, GPIO_FUNC_SPI);
gpio_set_function(SCK_PIN, GPIO_FUNC_SPI);
gpio_init(SS_PIN);
gpio_set_dir(SS_PIN, GPIO_OUT);
gpio_put(SS_PIN, 0); // this display is low on inactive
while(true)
{
printf("VCOM = %b \n", vcom_bool_);
gpio_put(SS_PIN, 1);
// Clear the display
uint8_t buf[2];
if(vcom_bool_)
{
buf[0] = 0b01100000;
vcom_bool_ = false;
}
else
{
buf[0] = 0b00100000;
vcom_bool_ = true;
}
buf[1] = 0b00000000;
spi_write_blocking(spi0, buf, 2);
gpio_put(SS_PIN, 0);
sleep_ms(10);
sleep_ms(500);
}
}
Display and wiring are ok, because when I run example code from Adafruit (it is using Arduino's libraries) it works.
I follow this documentation from Sharp: https://www.sharpsde.com/fileadmin/products/Displays/2016_SDE_App_Note_for_Memory_LCD_programming_V1.3.pdf
I also reviewed the code from Adafruit and the SPI communication seems to be done in the same way.
What am I doing wrong?
Is there some issue with using Pico libraries for Arduino Nano RP2040? I did I2C communication in the same way (Pico/RP2040 libraries, .uf2 copied to Arduino Nano RP2040) and it worked.