Difference between use of USART module and bitbang

[akokyaw]

Hi,
I found that 16F877 has USART module for serial communication. For this application, I have two options for writing code:
(1) by using USART registers such as BRGH, SPBRG (hardware)
(2) by using #use rs232(baud=9600, xmit=PIN_A3, rcv=PIN_A2) (software)

I believe there are some major differences. I feel that bitbang is easier to use. Does anyone know about the difference between use of USART module (hardware) and bitbang (software)? What are the advantage and disavantage?

Thank you,
ako

[asmallri]

The #use RS232 statement will use the embedded hardware UART if the tx and rx pins you define are the same as the ones used by the hardware and provided you do not use the force SW flag.

Wherever possible you should use the HW UART. If you use the software UART you have to be continuously calling kbhit() at multiple times the bit rate to ensure you do not lose characters or bits.

If you want to use a Rx interrupt handler then you need to use the HW UART as the SW implementation does not support Rx interrupts.
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Regards, Andrew

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[akokyaw]

Hi,
Thank for reply, Andrew. Now, I understand that bitbang (software) has to use initialization routine while USART module (hardware) has to use interrupt such as (TXIF). Anyway, CCS's printf function is intelligent and useful bitbang.
what condition we must use USART module except we need interrupt?

Regards,
ako

[asmallri]