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garyzheng
Joined: 22 Jul 2004
Posts: 25
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| why rs232 transmission will let the programm out of control |
 Posted: Thu Jan 06, 2005 4:00 pm |
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I am working on Wireless sensors project. So when I used the ICD2 as the debugger and debug the program everything run good(including RS232). But When I burn the program into MCU, and power up, It will be out of control when printf some string(Such as "Self-Calibration Succeed"!)
When I cut the printf, putc command, the program looks work. So Someone can tell me how to solve this problem. I had to use Rs232 to connecting with PC(shut down the interrupts(Int_TBE)?or when I check the RCSTA, i will find FERR is set, but I can not clear it cause I don't where my program had been after the command "printf"?
whether I can try to write something in the #int_tbe RS232_TX_Handler()?
By Using the C language, i sometimes will confused whether the after sending the data through RS232, and TX_buffer is empty, whether it will cause interrupts by MCU?
Or the baudrate I used is only 9.6kb, So when I printf a string(30bytes). how it will cause OERR set (transmission of RS232 is over speed )?
Thank u for your idea:) |
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Ttelmah
Guest
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| Re: why rs232 transmission will let the programm out of cont |
| Posted: Fri Jan 07, 2005 3:22 am |
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| garyzheng wrote: | I am working on Wireless sensors project. So when I used the ICD2 as the debugger and debug the program everything run good(including RS232). But When I burn the program into MCU, and power up, It will be out of control when printf some string(Such as "Self-Calibration Succeed"!)
When I cut the printf, putc command, the program looks work. So Someone can tell me how to solve this problem. I had to use Rs232 to connecting with PC(shut down the interrupts(Int_TBE)?or when I check the RCSTA, i will find FERR is set, but I can not clear it cause I don't where my program had been after the command "printf"?
whether I can try to write something in the #int_tbe RS232_TX_Handler()?
By Using the C language, i sometimes will confused whether the after sending the data through RS232, and TX_buffer is empty, whether it will cause interrupts by MCU?
Or the baudrate I used is only 9.6kb, So when I printf a string(30bytes). how it will cause OERR set (transmission of RS232 is over speed )?
Thank u for your idea:) |
OERR, and FERR, are _receive_ status bits.
It sounds as if the receive line coming into the processor, is floating low, or seeing noise, thereby giving a continuous 'error' state on the receive (not the transmit). I'd be looking at the ground connection between the RS232 tranceiver circuiot, and the processor. The probability is that the ICD wiring, is making a connection, and preventing this problem. Presumably your code has perhaps a receive interrupt, with no handler present, or the data not being read (and without the 'ERRORS' directive in the RS232 setup line), so the system is sitting looping in the receive handler, and can never transmit.
Best Wishes |
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GARYzhengabc
Guest
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| I had to #int_RDA handler |
| Posted: Sat Jan 08, 2005 3:51 pm |
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I think the problem laid on the RS232 TX mode right now, someone used int_tbe before? I want to know the int_tbe working procession.
let me guess the procession: when the TXREG is empty, it will set the interrupt flag on INTCON register and go into int_tbe handler? So what I do is to clear the interrupt flag for int_tbe,right? whether I should write some program to handle the RS232 transmission?
Formerly, I just used putc() or printf() function. it totally can work. but right now, i combined several interrupts together,such as int_ext,int_rda,int_timer1 together, it can work great under debugger mode, but i can not work when I burn program into MCU:)
your idea is I should connect the "ground" between PC and RS232(max3232) and MCU? |
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Ttelmah
Guest
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| Re: I had to #int_RDA handler |
| Posted: Sun Jan 09, 2005 3:00 am |
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| GARYzhengabc wrote: | I think the problem laid on the RS232 TX mode right now, someone used int_tbe before? I want to know the int_tbe working procession.
let me guess the procession: when the TXREG is empty, it will set the interrupt flag on INTCON register and go into int_tbe handler? So what I do is to clear the interrupt flag for int_tbe,right? whether I should write some program to handle the RS232 transmission?
Formerly, I just used putc() or printf() function. it totally can work. but right now, i combined several interrupts together,such as int_ext,int_rda,int_timer1 together, it can work great under debugger mode, but i can not work when I burn program into MCU:)
your idea is I should connect the "ground" between PC and RS232(max3232) and MCU? |
The interrupt handler automatically clears the interrupt flag for you. All you need to do, is write the next character to the chip.
Yes, connecting the grounds between circuits, is _vital_ (unless you are using certain types of differential signalling).
What you are describing, is a 'classic' problem, where if the ICD, is attached, there is automatically a ground connection made, but without this connection the system is now dependant on there being a seperate connection.
Best Wishes |
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