User's Manual

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When a read is completed successfully, SystemController update the modbus registers with the read value. If no tag is detected then
the channel data is set to 0's.
7.5 Communication Bus Drivers
7.5.1 MODBUS Interface
The UART4 module is configured to be used for modbus communication on the P-BUS. The UART4 is configured to run at 115200
baud rate, no parity and one stop bit.
The driver is developed to be interrupt driven and non-blocking functions to be suitable for use with the QP frame work. Timer
module is also imported from the same project where this timer module is required for the UART driver operations.
The RFID reader board is a slave modbus device. The modbus interface is implemented in QpModbusServer active object.
7.5.2 SPI Interface
The SPI port is used for communication with the RFID transceiver chip. The SPI driver is used and accessed by ReaderController
active object to read and write to the RFID transceiver chip.
The SPI port is configured to run at 2MHz, 8 bit data, SPI clock mode is set to mode 0 (Serial output data changes on transition from
idle clock state to active clock state and Idle state for clock is a low level; active state is a high level) and Input data is sampled at end
of data output time.
The SPI driver is developed to be interrupt driven and non-blocking functions to be suitable for use with the QP frame work.