FPC BM-Lite example application

This is a port of FPC BM-Lite Development Kit to Nordic nRF52840-DK development board. FPC BM-Lite module connected to the dev board by SPI interface.

There are 3 main folders in the project:

• BMLite_example - main HW-independed application
• HAL_Driver - implementation of HW-dependent functions

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Platform-independent interface functions

Platform-independent interface implemented in platform.c

Platform function	Description
bool platform_init(uint32_t speed_hz)	Initilalizes hardware
void platform_bmlite_reset(void)	Implements BM-Lite HW Reset
fpc_bep_result_t platform_bmlite_send(uint16_t size, const uint8_t *data, uint32_t timeout, void *session)	Send data packet to FPC BM-LIte
fpc_bep_result_t platform_bmlite_receive(uint16_t size, uint8_t *data, uint32_t timeout, void *session)	Receive data packet from FPC BM-LIte. If timeout = 0, the function will wait for data from BM-Lite indefinitely. The waiting loop will be breaked if hal_check_button_pressed() returns non-zero value. It is recommended to do HW or SW reset of BM-Lite if platform_bmlite_receive() returns FPC_BEP_RESULT_TIMEOUT in order to return is into known state.

Currently platform_bmlite_send() and platform_bmlite_receive() are implemented for SPI interface. For UART interface there is no need to wait for IRQ pin ready. However because in UART mode there is no signal from FPC-BM-LIte that it will send data, I would recommend to use UART interrupt or DMA to receive data from UART and store it to a separate buffer and read data in platform_bmlite_receive() from that buffer. Activation UART data reading only inside platform_bmlite_receive() could lead to loosing some incoming data and causing HCP protocol errors.

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HAL implementation

For porting the project to a new microcontroller, all functions from bmlite_hal.h should be implemented.

Functions must be implemented:

HAL Function	Description
void hal_board_init(uint32_t speed_hz)	Initialize GPIO, System timer, SPI
void hal_bmlite_reset(bool state)	Activate/Deactivate BM-Lite RST_N pin (Active Low)
fpc_bep_result_t hal_bmlite_spi_write_read(uint8_t *write, uint8_t *read, size_t size, bool leave_cs_asserted)	SPI data exchange
bool hal_bmlite_get_status(void)	Return status of BM-Lite IRQ pin (Active High)
void hal_timebase_init(void)	Initialize system clock with 1 msec tick
uint32_t hal_timebase_get_tick(void)	Read currect system clock value
void hal_timebase_busy_wait(uint32_t ms)	Delay for ms msec

Optional functions for implementing user interface in BM-Lite example application:

HAL Function	Description
uint32_t hal_get_button_press_time(void)	How long UI button was pressed last time. Also it should reset button pressed time counter
uint32_t hal_check_button_pressed(void)	Used for breaking waiting in platform_bmlite_receive() if returns non-zero
void hal_set_leds(platform_led_status_t status, uint16_t mode)	Set LED(s) state according to status and mode.

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Some notes about FPC BM-Lite HW interface

• BM-Lite support both UART and SPI communication interface. BM-Lite automatically detects the specific communication interface in use. However, it is not possible to use both interfaces at the same time!
• IRQ pin is used in SPI mode only as FPC BM-Lite Ready-to-Transmit signal. The module set it to High when it has some data to send and set it to Low when data packet is sent.