Radio

To interface with the radio present on the Botoks platform (ZL70550) we developed a rudimentary driver. This library is capable of executing calibration, transmitting and receiving packets.

First the driver needs to be initialized using zl70550_init() next the common registers have to be restored using zl70550_restore_state() and the operating frequency has to be set zl70550_set_frequency().

With the registers in the correct state now calibration can be executed zl70550_calibrate(). Calibration is only executed once on the first boot, afterwards it applies the previously determined calibration. This calibration is stored in FRAM.

After calibration the radio is fully operational and can transmit zl70550_packet_transmit() or receive zl70550_packet_receive().

void zl70550_init()

Initialize ZL70550

Initializes the GPIO and SPI to communicate with the ZL70550. Afterwards the ZL70550 is reset.

void zl70550_restore_state()

Restore the ZL70550’s registers to a know state

Initializes the common registers required for operation. Operating frequency still has to be configured separately. Needs to be executed after zl70550_init() but before the device is used.

void zl70550_set_frequency()

Set operation frequency

Sets the operating frequency to 869.7 Mhz. Needs to be executed after zl70550_init() but before the device is used.

void zl70550_packet_receive(uint8_t *rx_buffer, bool forever)

Receive packet

Function that can be used to receive a packet to a provided rx_buffer. Additionally it can operate in a perpetual loop with the forever flag. Hamming encoding is enabled.

Parameters

  • rx_buffer: Output: Buffer in which the data will be stored.

  • forever: Flag to signal a perpetual receive loop.

void zl70550_packet_transmit(uint8_t *data, uint16_t length)

Transmit a packet

Transmits the data contained in the data parameter with length length. CSMA is disabled and Hamming encoding is enabled.

Parameters

  • data: Data to transmit

  • length: Length of the data to transmit

void zl70550_calibrate()

ZL70550 Calibration Calibration routine

Execute the required calibration routine on the ZL70550. It calibrates the following:

  • Current reference

  • RCO

  • VCO amplitude

  • VCO frequency

  • Peak detector;

  • Antenna output

  • LNA

  • RC filter

  • FSK frequency deviation