CCS interrupt rda

miguel111 · Joined: 06 Nov 2014 Posts: 2

hi guys,

I need your help about ccs compiler and rs232 preprocessor directives.
1. can i use rs232 directive on pins without uart hardware ?

if 1 is possible,

2. can i use rda interrupt?

Thanks a lot!

Cool

dyeatman · Joined: 06 Sep 2003 Posts: 1934 Location: Norman, OK

The answer is yes and no

You can specify non UART pins and the compiler will generate a
software UART for those pins. However, a software UART cannot
use the standard RDA interrupts.
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asmboy · Joined: 20 Nov 2007 Posts: 2128 Location: albany ny

You might also consider reliability of SOFT uarts.....

If your program has significant time domain complexity,
and especially if it has other interrupts enabled, character
reception may fail intermittently, and transmitting may produce
mis-framed output characters. the lower the baud rate the more likely
the latter situation is to occur.

summary: serious projects do NOT make use of soft uarts
unless GREAT care is taken in design to work around the numerous
situations that can cause malfunction in runtime.

temtronic · Posted: Thu Nov 06, 2014 6:06 pm

As others have said it's a yes and no answer though really you should look at another PIC if you need more than one UART with interrupt capacity. Several have 2 UARTs, like the 18F46K22 and you can add additional peripheral UARTs with say I2C<>UART devices.
If you explain the scope of your project we can better direct you to a better solution.
uChip make a LOT of PICs and the CCS compiler handles them all...

hth
Jay

miguel111 · Joined: 06 Nov 2014 Posts: 2

Ttelmah · Joined: 11 Mar 2010 Posts: 19552

Line 2 of D Yeatman's answer:
"However, a software UART cannot use the standard RDA interrupts."

Note the word 'cannot'....

Doing RS232 in software, has big limitations. Half duplex only, unless a 'tick' based approach is used, and a lot of work.

However a thing is 'screaming' at me. You have the 26J50. This has two hardware UART's, and the second of these is configurable to use just about any pin on the chip.

So, what pins are the sim5320A connected to?.
TX on 5320 to what pin on PIC?
RX of 5320 to what pin on PIC?.

With this, we can tell you how to configure the second _hardware_ UART to talk to this.

The re-mappable peripheral ability of the 26J50, is probably 'why' the device is not connected to the UART1 pins.

ezflyr · Joined: 25 Oct 2010 Posts: 1019 Location: Tewksbury, MA

Hi,

Seriously, if you are asking such basic questions as you are about to embark on a PIC/GSM project, I would take about ten steps back and start off with something much more simple. If you start with a PIC/GSM project as your very first embedded effort, you are almost 100% guaranteed to fail!

I really don't want to throw cold water on you, but I am being totally realistic based on previous attempts at this type of project by other 'newbies' here on the forum!

John