SI4432 driver

Description

This driver was written for module, based on SI4432 IC, which is RF transciever. Corrently only STM32`s HAL is supported as a communication layer, but another IO-layers can be developed easily due to modular design. For example, all you need to port this lib to Arduino - implement custom SI44_Read, SI44_Write and SI44_IO_Init functions. If you do that, please send me a pull request! Supported only transmit with Packet Handler active. Length of payload automatically added to packet.

How to work with this lib

Example bellow for STM32 CubeMX preconfigured project.

1. Clone this repo into you Drivers/ directory:

   $ cd Drivers/
   $ git clone https://github.com/udik-chudik/SI4432.git

2. Add SI4432.h on top of your main.c file.
3. Initialize communication by adding the folowing lines into you main function:

    SI44_Init(&hspi2, GPIOB, GPIO_PIN_12);

Here we assume that module has been connected to appropriate pind, dedicated to hspi2, and NSS (slave select pin, with low active) connected to PIN12 of SPIOB.

4. Now lets configure out:

   /* General config */
   si44_config conf;
   conf.encoding_options = 0;
   conf.modulation_source = SI44_MODULATION_SOURCE_FIFO;    //Use FIFO mode
   conf.modulation_type = SI44_MODULATION_TYPE_GFSK;        //Modulation GFSK
   SI44_SetConfig(conf);
   /* Packet handler config */
   si44_ph_config ph_conf;
   ph_conf.path = SI44_PH_PATH_TX_ONLY;
   ph_conf.preambule_length = 8;                //Preambule length in nibbles (8 * 4 -> 32 bits)
   ph_conf.sync = SI44_PH_SYNC_2;               //Use 2 bytes (3 and 4) length sync-word
   ph_conf.header = SI44_PH_HEADER_OFF;         //Don`t use header
   ph_conf.crc = SI44_PH_CRC_DATA_ONLY;         //Use CRC, computed over data only
   ph_conf.crc_type = SI44_PH_CRC_TYPE_IBM16;   //Use IBM16 as a CRC type
   SI44_SetPHConfig(ph_conf);

5. Set up frequency, frequency deviation, data rate and TX power:

   SI44_SetFrequency(433.95);               //Set up 433.95 MHz
   SI44_SetDataRate(2400);                  //Set up data rate as 2400 bit/sec
   SI44_SetFrequencyDeviation(2400);        //Set deviation to 2400 Hz (BH=1 for baud=2400
   SI44_SetTXPower(SI44_TX_POWER_11dBm);    //Set TX power to 11dBm (12.5 mW)

6. Now we are ready to send a message!

   uint8_t message[] = "Hello world!\n";
   SI44_SendPacket(message, sizeof(message));

   With configuration above, resulting transmittes structure will be:

   [10101010...][2d d4][0c][Hello world!\n][crc]