Trouble using 16f628a….

Ken · Guest

Hi all,

Here are my two questions…

1. Can I use TX pin of the USART as I/O if I’m only using it RX pin?? Should I remove xmit pin declaration like this #use rs232(baud=2400, rcv=PIN_B1) to do so??

2. Can I use MLCR/RB5 pin as I/O(source or sink current to drive LED)…..if yes, then how do I reset the uC??

Thanks

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Ken · Guest

Hi PCM programmer,

Thanks a lot...I appreciate your help....

So far I've been using
#use rs232(baud=2400, xmit=PIN_B2, rcv=PIN_B1), whats the difference between the below one...
#use rs232(baud=2400, xmit=PIN_B2, rcv=PIN_B1, ERRORS)

Thanks again

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

http://www.ccsinfo.com/forum/viewtopic.php?t=19759&highlight=overrun

Ken · Guest

My last question...

I was going to use PortB to drive 7 segment display....but since TX pin of the USART is not going to set free, I will use some pin of PortA for software USART!! Can I make MCLR/RB5 pin as RX input??

Another problem...I'm will be using RB0/INT pin as input for external interrupt, at the same time I will be sending data for 7 segment display using output_b() function, how can I make it work beacuse outport_b() will send a whole byte of data so RB0/INT pin will become output, which I really don't want!!

Thanks

Ttelmah · Guest

This is down to TRIS.
In CCS, there are three operating 'modes' for tris control. The default (standard_io), has the pins change direction, when accessed. If you output a byte, the tris for the whole register gets set. However you can take control of the tris register yourself. If you select #use fixed_io(b_outputs=PIN_B1,PIN_B2,PIN_B3,PIN_B4,PIN_B5,PIN_B6,PIN_B7)
Then the tris BITS are cleared for the top seven bits, and the bottom bit is set, making this pin an input. You can then output a byte on the port, and only the top seven bits of the byte, will actually be output, leaving B0, to operate as an input. You can do the same, with #use fast_io(b), and then setting tris, with set_tris_b(0b00000001);

Best Wishes

Ken · Guest

Thanks...what about my first question.

Regards

Ttelmah · Guest

On the UART, declare a normal #use RS232 statement, with both pins declared. Otherwise the software UART will be used. You can then use the TX pin _as an input_, by changing the TRIS for this pin to '1' (this overrides the peripheral use of the pin). Alternatively, turn off the transmit 'side' of the UART, by clearing the TXEN bit, and you can then use the bit as I/O.

Best Wishes