ESP32/STM32 SPI with ST7701S: first command not sent, sequence stops

[Ameni]

Hello,

I am using an ST7701S LCD over 3-wire SPI (CS, SCK, SDA) with my STM32.

When I send the initialization commands from my ESP, I noticed the following:

• The first command of the sequence is not sent.

• The program seems to stop at the second stage, around the 100th command.

SPI is configured in master mode, polling (no DMA, no interrupts).

Example of the write function:

void ST7701_Write(uint8_t dc, uint8_t data) {
uint16_t value = ((dc & 0x01) << 8) | data;
HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_RESET);
HAL_SPI_Transmit(&hspi2, (uint8_t *)&value, 1, HAL_MAX_DELAY);
HAL_GPIO_WritePin(LCD_CS_GPIO_Port, LCD_CS_Pin, GPIO_PIN_SET);
}

Questions:

1. Could the first command being skipped be due to HAL/SPI initialization or state?

2. What is the recommended method to ensure all commands are reliably sent over 3-wire SPI to ST7701S?

Thank you for your help.

[mƎALLEm]

Hello,

In next time please use </> to share a code. Please read How to write your question to maximize your chances to find a solution

I invite you to edit your post to comply with the community rule.

Thank you for your understanding.