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Jon Fick
Joined: 09 Dec 2003
Posts: 5
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| ERROR keyword and RS232_ERROR variable |
 Posted: Sat Dec 27, 2003 10:26 pm |
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Searched the archives and can't find any relavent posts...
In the 18F252 I'm using the hardware UART (using the Rx and Tx pins) and a software UART (using another set of pins,) thus I have two #USE RS232 statements.
For the hardware UART I need to know framing errors, etc, so I inclue the ERROR keyword on the #USE RS232 statement, and therefore any errors are written to the variable called RS232_ERRORS.
For the software UART I need to read the ninth bit for the particular protocol I'm using, so I again need to use the ERROR keyword and examine the RS232_ERRORS variable.
I'm thinking that there is only one variable that ERRORS sets and that I will have conflicts.
Does anyone have experience with this? Thanks.
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Jon Fick |
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ttelmah
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| Re: ERROR keyword and RS232_ERROR variable |
| Posted: Sun Dec 28, 2003 7:40 am |
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| Jon Fick wrote: | Searched the archives and can't find any relavent posts...
In the 18F252 I'm using the hardware UART (using the Rx and Tx pins) and a software UART (using another set of pins,) thus I have two #USE RS232 statements.
For the hardware UART I need to know framing errors, etc, so I inclue the ERROR keyword on the #USE RS232 statement, and therefore any errors are written to the variable called RS232_ERRORS.
For the software UART I need to read the ninth bit for the particular protocol I'm using, so I again need to use the ERROR keyword and examine the RS232_ERRORS variable.
I'm thinking that there is only one variable that ERRORS sets and that I will have conflicts.
Does anyone have experience with this? Thanks. |
The RS232_ERRORS byte, will refer to the last getc, and next putc. This does imply, that when dealing with a combined hardware/software system, you would need to disable the hardware receive (if using interrupt driven code), while doing a software receive (but this is normally necessary anyway, in order to maintain the required timing accuracy).
You really have to only use the streams 'one at a time', or the serial handler won't work. Hence the shared nature of the variable is not a problem. If you want completely seperate UARTs, with buffering etc., look instead at a chip with dual hardware UARTs, or consider using an SPI UART (such as the MAX3110).
Best Wishes |
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| Posted: Sun Dec 28, 2003 7:48 am |
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| That's more or less what I thought might be the case...use one at a time. And, that's not an issue. When using the software UART, I can disable the hardware UART interrupt and clear the error variable. I'm only doing one thing at a time anyway. Thanks. |
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