I am using LPC2129 CAN QuickStart Board and trying to get UART work. But I found
the chip on the board is LPC2194/01, not LPC2129. And I did some research on the
LPC2194/01 baudrate setting up for the rev 01 chip. Based on the baudrate
calculation in the LPC2194 user manual, I set up the UART0 register as
following:
PCLK is 12,000,000 HZ Expected bitrate is 38400
U0LCR = 0x83;
U0DLL = 13;
U0DLM = 0;
U0FDR = 0x00000021; //DIVADDVAL = 1; //MULVAL = 2;
U0LCR = 3;
I spent a whole day to figure this out, and I even tried the UART sample
applications from Embedded Artists website, but always got trash data in the
terminal.
Any suggestions are welcomed and appreciated. Thank you!
-Tekkon
LPC2194 UART BaudRate Problem
Started by ●October 13, 2011
Reply by ●October 15, 20112011-10-15
>
> I spent a whole day to figure this out, and I even tried the UART sample applications from Embedded Artists website, but always got trash data in the terminal.
>
> Any suggestions are welcomed and appreciated. Thank you!
>
Storage scope. Tx a char, (eg. 0xAA) and capture it. Measure the bit width, number of bits etc. and then bodge your register values appropriately.
Rgds,
Martin
> I spent a whole day to figure this out, and I even tried the UART sample applications from Embedded Artists website, but always got trash data in the terminal.
>
> Any suggestions are welcomed and appreciated. Thank you!
>
Storage scope. Tx a char, (eg. 0xAA) and capture it. Measure the bit width, number of bits etc. and then bodge your register values appropriately.
Rgds,
Martin
Reply by ●October 15, 20112011-10-15
> PCLK is 12,000,000 HZ Expected bitrate is
38400
Make sure that it is 12 MHz, the APBDIV will control this.
I assume your crystal is 12 MHz and that your are not using the PLL. With the APBDIV set to default you will have a PCLK that is 1/4 of the cpu clock, therefore my guess is that your PCLK is 3MHz.
--
Kevin
Make sure that it is 12 MHz, the APBDIV will control this.
I assume your crystal is 12 MHz and that your are not using the PLL. With the APBDIV set to default you will have a PCLK that is 1/4 of the cpu clock, therefore my guess is that your PCLK is 3MHz.
--
Kevin
Reply by ●October 15, 20112011-10-15
--- In l..., "Kevin" wrote:
> > PCLK is 12,000,000 HZ Expected bitrate is 38400
>
> Make sure that it is 12 MHz, the APBDIV will control this.
> I assume your crystal is 12 MHz and that your are not using the PLL. With the APBDIV set to default you will have a PCLK that is 1/4 of the cpu clock, therefore my guess is that your PCLK is 3MHz.
>
> --
> Kevin
>
In the files section you can find 'baudcalc.zip' - a very nice windows program for calculating the various values. There is also baudratecalc.xls - a spreadsheet that finds the optimum values.
Baudcalc gives the values (so does the spreadsheet)
DLL = 0x10
DLM = 0x00
FDR = 0x92
The final baud rate will be 38352 with an error of 0.124 percent.
I haven't actually used baudcalc to get values for my projects but I have used the spreadsheet version and I know it gets the right numbers (at least for my projects).
Richard
> > PCLK is 12,000,000 HZ Expected bitrate is 38400
>
> Make sure that it is 12 MHz, the APBDIV will control this.
> I assume your crystal is 12 MHz and that your are not using the PLL. With the APBDIV set to default you will have a PCLK that is 1/4 of the cpu clock, therefore my guess is that your PCLK is 3MHz.
>
> --
> Kevin
>
In the files section you can find 'baudcalc.zip' - a very nice windows program for calculating the various values. There is also baudratecalc.xls - a spreadsheet that finds the optimum values.
Baudcalc gives the values (so does the spreadsheet)
DLL = 0x10
DLM = 0x00
FDR = 0x92
The final baud rate will be 38352 with an error of 0.124 percent.
I haven't actually used baudcalc to get values for my projects but I have used the spreadsheet version and I know it gets the right numbers (at least for my projects).
Richard
