\# Author Boris Skegin
\# Issued under the terms of the GPL v2 License or any later version
.TH hm2_pktuart_send "3hm2" "2016-02-29" "LinuxCNC Documentation" "Hostmot2"
.SH NAME

hm2_pktuart_send \- write data to a Hostmot2 PktUART

.SH SYNTAX
.nf
.B #include <hostmot2-serial.h>
.HP
int hm2_uart_send(char *name,  unsigned char data[], rtapi_u8 *num_frames, rtapi_u16 frame_sizes[])

.SH DESCRIPTION
\fBhm2_pktuart_send\fR writes "num_frames"  of data to the PktUART "name" from the 
buffer "data" with frame sizes preset in "frame_sizes[]" array.
"frame_sizes[]" array should not have more than 16 elements as this is the highest
number of frames that can be sent out in the so called "burst mode".

Note that the PktUART MaxFrameSize is 1024 bytes as hard-coded in hostmot2.vhd .

"name" is a unique string given to each PktUART during hostmot2 setup. The names of 
the available channels are printed to standard output during the driver loading 
process and take the form:                                    
hm2_<board name>.<board index>.pktuart.<index> For example hm2_5i25.0.pktuart.0 .

This function sends a variable number of PktUART packets (less or equal 16) from 
the the specified channel. It should be used inside a realtime HAL component
registered with the main hostmot2 driver using the function hm2_pktuart_setup 
in the setup code. 

.SH RETURN VALUE
Returns the number of bytes sent on success and negative error codes on failure.

"num_frames" which pointer is passed by value is set to the number of successfully 
datagrams sent out.

Negative error codes are:
.TP 
.B -1 - low level read/write error
.TP
.B -EINVAL - any PktUART configuration error per instance
.TP
.B -HM2_PKTUART_TxSCFIFOError - Tx Send Count FIFO Error
.TP
Numeric values of HM2_PKTUART_ error codes are defined in src/hal/drivers/mesa-hostmot2/pktuart_errno.h .


.SH SEE ALSO
\fBhm2_pktuart_setup\fR(3hm2), \fBhm2_pktuart_read\fR(3hm2)
.TP
See src/hal/drivers/mesa_pktgyro_test.comp for an example usage.
