XE8806A SEMTECH [Semtech Corporation], XE8806A Datasheet - Page 114

• Manufacturer Part Number: XE8806A
• Description: Ultra Low-Power Low-Voltage
• Manufacturer: SEMTECH [Semtech Corporation]

15.8.4
The transmission and reception software can be driven by interruption or by polling the status bits.
Interrupt driven reception: each time an Irq_uart_Rx interrupt is generated, a new word is available in RegUartRx.
The register has to be read before a new word is received.
Interrupt driven transmission: each time the contents of RegUartTx is transferred to the transmission shift register,
an Irq_uart_Tx interrupt is generated. A new word can then be written to RegUartTx.
Reception driven by polling: the UartRxFull bit is to be read and checked. When it is 1, the RegUartRx register
contains new data and has to be read before a new word is received.
Transmission driven by polling: the UartTxFull bit is to read and checked. When it is 0, the RegUartTx register is
empty and a new word can be written to it.
15.9 Software hints
Example of program for a transmission with polling:
1. The RegUartCmd register and the RegUartCtrl register are initialized (for example: 8 bit word length, odd
2. Write a byte to RegUartTx.
3. Wait untill the UartTxFull bit in RegUartTxSta register equals 0.
4. Jump to 2 to writing the next byte if the message is not finished.
5. End of transmission.
Example of program for a transmission with interrupt:
1. The RegUartCmd register and the RegUartCtrl register are initialized (for example: 8 bit word length, odd
2. Write a byte to RegUartTx.
3. After an interrupt and if the message is not finished, jump to 2
4. End of transmission.
© Semtech 2006
Asynchronous Reception
read of RegUartRx (software)
parity, 9600 baud, enable UART transmission).
parity, 9600 baud, enable UART transmission).
reguartrx_shift
UartRxBusy
RegUartRx
Irq_uart_Rx
UartRxFull
shift clock
Interrupt or polling
Rx
start
b0
Figure 15-2. UART reception timing diagram.
b6/7
15-7
parity
stop
word 1
word 1
XE8806A/XE8807A
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