hm2_pktuart_setup

NAME
SYNTAX
DESCRIPTION
RETURN VALUE
SEE ALSO
FUTURE DEVELOPMENT

NAME

hm2_pktuart_setup − setup a Hostmot2 PktUART instance

SYNTAX

int hm2_pktuart_setup(char *name, int bitrate, rtapi_s32 tx_mode, rtapi_s32 rx_mode, int txclear, int rxclear)

DESCRIPTION

hm2_pktuart_setup Setup the bitrate for the PktUART named "name". "name" is a unique string given to each PktUART during hostmot2 setup. The names of the available UARTs 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 .

Hostmot2 UARTs are good to about 10 Mb/sec, but higher data rates (with any UART) trade speed for susceptibility to impulse noise.

The PktUART function allows different RX and TX bitrates, but that is not currently supported by this driver.

tx_mode is bit mask defined in the Hostmot2 regmap:

Bit 21

FrameBuffer Has Data

Bits 20..16 Frames to send
Bits 15..8 InterFrame delay in bit times

Bit 7

Send busy, Transmit Logic active

Bit 6

Drive Enable bit (enables external RS-422/485 Driver when

set)

Bit 5

Drive enable Auto (Automatic external drive enable)

Bit 4

SCFIFO Error

Bits 3..0 Drive enable delay (delay from asserting drive enable

to start of data transmit. In CLock Low periods

rx_mode is bit mask defined in the Hostmot2 regmap:

Bit 21

FrameBuffer has data

Bits 20..16 Frames received
Bits 15..8 InterFrame delay in bit times

Bit 7

Rx Logic active

Bit 6

RXMask

Bit 5 Unused

Bit 4

RCFIFO Error

Bit 3

RXEnable (must be set to receive packets)

Bit 2

RXMask Enable (enables input data masking when transmitting)

Bit 1

Overrun error (no stop bit when expected) (sticky)

Bit 0

False Start bit error (sticky)

rx_mode and tx_mode registers are currently write-only. One can get the instance number of a PktUART instance with the help of hm2_get_pktuart function in order to read and write to Rx and Tx registers.

To write only to the tx_mode DriveEnable bit call this function with the bitrate unchanged and -1 as the rx_mode To change bitrate without altering mode settings send -1 to both modes.

txclear==1 aborts any sends in process, clears the data FIFO and clears the send count FIFO.

rxclear==1 aborts any receives in process, clears the data FIFO and clears the receive count FIFO.

txclear!=1 or rxclear!=1 lets the corresponding registers unchanged.

RETURN VALUE

Returns 0 on success and -1 or -EINVAL on failure.

SEE ALSO

man hm2_pktuart_send, man hm2_pktuart_read
See src/hal/drivers/mesa_pktgyro_test.comp for an example usage.

FUTURE DEVELOPMENT

This function is subject to change as digital filters will be added on the Rx UART, and bit rate register will gain a 12 bit field for the input filter constant.