source: rtems/c/src/lib/libbsp/lm32/milkymist/Documentation/uart.txt @ 8affb5a9

4.115
Last change on this file since 8affb5a9 was 8affb5a9, checked in by Joel Sherrill <joel.sherrill@…>, on Aug 20, 2010 at 9:22:27 PM

2010-08-20 <yann.sionneau@…>

Add Milkymist BSP developed as part of GSOC 2010.

  • ChangeLog?, Makefile.am, README, bsp_specs, configure.ac, preinstall.am, Documentation/uart.txt, include/.cvsignore, include/bsp.h, include/system_conf.h, include/tm27.h, make/custom/milkymist.cfg, startup/linkcmds: New files.
  • Property mode set to 100644
File size: 609 bytes
Line 
1Initialization :
2
3        set the CSR_UART_DIVISOR to the correct VALUE,
4        depending on the internal frequency of the LatticeMico32 softcore.
5
6        for the ML401 board, this value is calculated using this formula : clk_frequency/230400/16
7        clk_frequency  = 100000000 Hz
8        => we must set CSR_UART_DIVISOR to 27
9
10How to send a byte to uart :
11
12void writechar(char c)
13{
14                CSR_UART_RXTX = c;
15                while(!(irq_pending() & IRQ_UARTTX));
16                irq_ack(IRQ_UARTTX);
17}
18
19How to receive a byte from uart :
20
21
22char readchar()
23{
24        char c;
25        while(!(irq_pending() & IRQ_UARTRX));
26        irq_ack(IRQ_UARTRX);
27        c = CSR_UART_RXTX;
28        return c;
29}
30
31
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