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+--- Thread: Problems with hardware UART (/showthread.php?tid=2338)
Problems with hardware UART - velostar - 2015-01-18
Hello,
in my private project I use the PIC18F45K22 with an external quartz clock of 8MHz.
Therein I use some capture (CCP) and timer routines from older projects (based on PIC 16F887 @ 8MHz).
In order to use this I made the following setting in the DS30 source software:
Settings.inc:
#define FOSC 8000000 ; 8MHz
…
config FOSC = HSMP ; external oscillator block medium power
config PLLCFG = OFF ; Oscillator used directly ( Disabled – 16F887 has no PLL )
…
After rebuilt in MPLAB I receive no errors.
Well done (?) - Speed measurement with CCP and used timers works fine.
But: In my program I use UART data communication with 9600 bps.
(UART1_Init(9600): This will initialize hardware UART1 module and establish the communication at 9600 bps.)
In my HyperTerminal program on PC I must change the Baud rate from 9600 to 38400 to receive accurate and readable messages. I don’t know what happens!!
My guess: 38400= 4x 9600! – PLL active? But I switched PLLCFG = OFF (s. above)
What’s going on?
RE: Problems with hardware UART - Mikael Gustavsson - 2015-01-19
Hello,
What if you clear the BRGH bit in the TXSTA register in your application?
RE: Problems with hardware UART - velostar - 2015-01-23
Hello,
thank you for supporting me. You are absolutly right.
I set BRGH_bit = 0 and the communication works prober.
UART_Init(9600) and Terminal baud rate = 9600
Thanks again!