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component mesa_uart "An example component demonstrating how to access the Hostmot2 UART";
description """This component creates 16 input and 16 output pins. It transmits
{name}.N.tx-bytes on the selected UART every thread cycle and reads up to 16
bytes each cycle out of the receive FIFO and writes the values to the associated
output pins. {name}.rx-bytes indicates how many pins have been written to.
(pins > rx-bytes simply hold their previous value)
This module uses the names= mode of loadrt declaration to specifiy which UART
instances to enable. A check is included to ensure that the count= option is
not used instead.
The component takes parameters in the form of a comma-separated
list of UART instance names, for example:
\\fB loadrt mesa_uart names=hm2_5i23.0.uart.0,hm2_5i23.0.uart.7\\fR
Note that no spaces are allowed in the string unless it is delimited by double
The UART instance names are printed to the dmesg buffer during the Hostmot2
setup sequence, one for each UART instance included in the bitfile loaded to
each installed card during the Hostmot2 setup sequence. Type "dmesg" at the
terminal prompt to view the output.
The component exports two functions, send and receive, which need to be added
to a realtime thread.
The above example will output data on UART channels 0 and 7 and the pins will
have the names of the individual UARTS. (they need not be on the same card, or
even the same bus).
Read the documents on "halcompile" for help with writing realtime components:""";
author "Andy Pugh";
license "GPL";
include <hostmot2-serial.h>;
pin in u32 tx-data-##[16] "Data to be transmitted";
pin out u32 rx-data-##[16] "Data received";
pin in s32 tx-bytes "Number of bytes to transmit";
pin out s32 rx-bytes "Number of Bytes received";
variable char *name; // UART name
option extra_setup yes;
function send;
function receive;
/* This uses the RTAPI_MP_ARRAY_STRING macro to load the list of UART channels
into an array. This is copied into the *name string of each */
char *uart_chans[18] = {0,};
RTAPI_MP_ARRAY_STRING(uart_chans, 16, "UART Channel names");
/* This function uses the hm2_uart_send function to transmit data see
man hm2_uart_send for more information. Data may be up to 64 bytes in size*/
unsigned char data[16];
int i, count;
count = tx_bytes;
if (count > 16) count = 16;
for (i = 0 ; i < count ; i++){
data[i] = tx_data(i) & 0x000000FF; //NB [] index for array and () for pin.
count = hm2_uart_send(name, data, count);
/* This function uses the hm2_uart_send function to transmit data.
See man hm2_uart_send for more information. 16 bytes in the Rx buffer*/
int i;
unsigned char data[16];
rx_bytes = hm2_uart_read(name, data);
for (i = 0 ; i < rx_bytes ; i++){
rx_data(i) = data[i];
EXTRA_SETUP(){ // the names parameters are passed in 'prefix'. You just have to know that.
if (prefix[0] == 'm'){ // should be the 'h' of hm2_....
rtapi_print_msg(0, "mesa_uart can not be loaded using the 'count' "
"parameter, see man mesa_uart for details\n");
return -1;
name = hal_malloc(strlen(prefix)+1);
strcpy(name, prefix);
// 250000bps, no delay, tx enable)
hm2_uart_setup(name, 250000, 0x40, -1);
return 0;
int get_count(void){
int i;
for (i= 0; uart_chans[i] != NULL && i < 16 ; i++){}
return i;
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