NRF24 Library Usage Guide

Check mirf.c for more details.

Prerequisites

Before using this library, ensure that you have the following:

• STM8 microcontroller development board.
• PlatformIO with STLink driver support
• NRF24 module connected to the STM8 board with appropriate wiring.

Configuration

Pins Configuration

Make sure to define the pins connected to the NRF24 module in the library using the following macros:

#define CE_PIN_LETTER GPIOC
#define CE_PIN_NUMBER GPIO_PIN_4
 
#define CSN_PIN_LETTER GPIOC
#define CSN_PIN_NUMBER GPIO_PIN_3

Adjust these macros based on your actual hardware configuration.

NRF Configuration

Set the NRF channel number and payload size using the following macros:

#define NRF_CHANNEL_NR 114
#define NRF_PAYLOAD_SIZE 32

Initialization

To initialize the NRF24 module, use the Nrf24_init() function. This function configures the CE/CS pins and SPI.

Nrf24_init();

Sending Data

To send data, use the Nrf24_send function. Provide the data array and a pointer to a boolean indicating the RX/TX state of the NRF module.

uint8_t data[NRF_PAYLOAD_SIZE] = { /* your data here */ };
bool PTX = /* true if in TX mode, false if in RX mode */;
Nrf24_send(data, &PTX);- STM8 libraries installed.

• Nrf24_setTADDR: Set the transmitting device address.
• Nrf24_addRADDR: Add more device addresses to receive.
• Nrf24_SetOutputRF_PWR: Set the transmission power.
• Nrf24_SetSpeedDataRates: Select between high-speed data rates.
• Nrf24_setRetransmitDelay: Set the auto retransmit delay.

Refer to the function descriptions in the code for more details on each configuration function.

Power Management

Control the power state of the NRF24 module using the following functions:

• Nrf24_powerUpRx: Power up the NRF module for receiving.
• Nrf24_powerUpTx: Power up the NRF module for transmitting.
• Nrf24_powerDown: Power down the NRF module.

Status and Checking

Use the following functions to check the status and monitor the communication:

• Nrf24_getStatus: Get the status register value.
• Nrf24_isSending: Check if the module is still sending.
• Nrf24_isSend: Check if sending has finished or retries are over.

Usage Example

The main.cpp file comes with an example on how to set up the NRF.

1. GPIO Configuration

First, configure the necessary GPIO pins for debugging LEDs and the button. Additionally, set up an interrupt for the button.

// Debuging LEDs
GPIO_Init(GPIOB, GPIO_PIN_1, GPIO_MODE_OUT_OD_LOW_FAST);
GPIO_Init(GPIOB, GPIO_PIN_2, GPIO_MODE_OUT_OD_LOW_FAST);
 
// Button
GPIO_Init(GPIOB, GPIO_PIN_0, GPIO_MODE_IN_PU_IT);
 
// Interrupt for button
EXTI_DeInit();
EXTI_SetExtIntSensitivity(EXTI_PORT_GPIOB, EXTI_SENSITIVITY_FALL_ONLY);
EXTI_SetTLISensitivity(EXTI_TLISENSITIVITY_FALL_ONLY);
 
enableInterrupts();
 
// Turn off LEDs
GPIO_WriteHigh(GPIOB, GPIO_PIN_1);
GPIO_WriteHigh(GPIOB, GPIO_PIN_2);

2. NRF24 Initialization

Initialize the NRF24 module and configure it based on your application requirements.

Nrf24_init();
bool PTX = 0;
 
Nrf24_config(&PTX);

3. Set Own and Receiver Addresses

Set the own address and the receiver address using 5 characters. Ensure the addresses are unique and match between the transmitter and receiver.

int ret;
 
ret = Nrf24_setRADDR((uint8_t *)"ABCDE");
if (ret != SUCCESS)
{
    while (1)
    {
        delay_ms(1);
    }
}
 
ret = Nrf24_setTADDR((uint8_t *)"FGHIJ");
if (ret != SUCCESS)
{
    while (1)
    {
        delay_ms(1);
    }
}

4. Configure Communication Parameters

Set the communication parameters such as data rate and retransmit delay.

Nrf24_SetSpeedDataRates(RF24_1MBPS);
Nrf24_setRetransmitDelay(0);

5. Main Loop

Implement the main loop to handle communication and LED control based on button presses.

uint8_t buf[32];
 
// Clear RX FiFo
while (1)
{
    if (Nrf24_dataReady() == FALSE)
    {
        break;
    }
    Nrf24_getData(buf);
}
 
while (1)
{
    // When the program is received, the received data is output from the serial port
    if (Nrf24_dataReady())
    {
        // Turns the led on when a packet is received if the button was clicked
        if (bIntFlag == 1)
        {
            bIntFlag = 0;
            GPIO_WriteLow(GPIOB, GPIO_PIN_1);
        }
        else
        {
            GPIO_WriteHigh(GPIOB, GPIO_PIN_1);
        }
 
        Nrf24_getData(buf);
 
        // The ESP is printing stuff so it takes a while to switch to RX mode.
        delay_ms(10);
 
        Nrf24_send(buf, &PTX);
 
        // Same here, delay a bit.
        delay_ms(10);
 
        while (!Nrf24_isSend(50, &PTX))
        {
            // If no ACK after the preconfigured retries, send again.
            Nrf24_send(buf, &PTX);
            delay_ms(10);
        }
    }
    // Wait a bit to check if the NRF received data.
    delay_ms(1);
}

Adjust the code as needed for your specific application logic and use case. Ensure that the button press detection and LED control match your hardware setup.