58 lines
3.9 KiB
Markdown
58 lines
3.9 KiB
Markdown
## FPC BM-Lite example application
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This is a port of [FPC BM-Lite Development Kit](https://www.fingerprints.com/solutions/access/bm-lite-development-kit/ "BM-Lite Development Kit") to Nordic nRF52840-DK development board. FPC BM-Lite module connected to the dev board by SPI interface.
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There are 3 main folders in the project:
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- [BMLite_example](BMLite_example) - main HW-independed application
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- [BMLite_sdk](BMLite_sdk) - FPC BM-Lite SDK
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- [HAL_Driver](HAL_Driver) - implementation of HW-dependent functions
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------------
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### Platform-independent interface functions
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Platform-independent interface implemented in [platform.c](BMLite_sdk/src/platform.c)
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| Platform function | Description |
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| :-------- | :-------- |
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| fpc_bep_result_t **platform_init**(void *params) | Initilalizes hardware |
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| void **platform_bmlite_reset**(void) | Implements BM-Lite HW Reset |
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| 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 |
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| 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. |
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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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------------
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### HAL implementation
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For porting the project to a new microcontroller, all functions from [bmlite_hal.h](BMLite_sdk/inc/bmlite_hal.h) should be implemented.
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#### Functions must be implemented:
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| HAL Function | Description |
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| :------------ | :------------ |
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| fpc_bep_result_t **hal_board_init**(void *params) | Initialize GPIO, System timer, SPI |
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| void **hal_bmlite_reset**(bool state) | Activate/Deactivate BM-Lite **RST_N** pin (***Active Low***) |
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| 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 |
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| bool **hal_bmlite_get_status**(void) | Return status of BM-Lite **IRQ** pin (***Active High***) |
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| void **hal_timebase_init**(void) | Initialize system clock with 1 msec tick |
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| uint32_t **hal_timebase_get_tick**(void) | Read currect system clock value |
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| void **hal_timebase_busy_wait**(uint32_t ms) | Delay for **ms** msec |
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#### Optional functions for implementing user interface in BM-Lite example application:
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| HAL Function | Description |
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| :------------ | :------------ |
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| uint32_t **hal_get_button_press_time**(void) | How long UI button was pressed last time. Also it should reset button pressed time counter |
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| uint32_t **hal_check_button_pressed**(void) | Used for breaking waiting in **platform_bmlite_receive()** if returns non-zero |
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| 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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------------
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### Some notes about FPC BM-Lite HW interface
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- 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!
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- **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.
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