HM2_UART_SETUP(3)

NAME
hm2_uart_setup - setup a Hostmot2 UART

SYNTAX

    #include <hostmot2-serial.h>
    int hm2_uart_setup(char* name, int bitrate, s32 tx_mode, s32 rx_mode);

DESCRIPTION

hm2_uart_setup Setup the bitrate for the UART named "name". "name" is a unique string given to each UART 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>.uart.<index>, for example hm2_5i23.0.uart.0. The minimum bitrate is approximately 50 bps, and the maximum around the FPGA frequency, 48 MHz for a 5I23. The UART 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 0..3:: TXEnable delay. TXEnable delay specifies the transmit data holdoff time from the TXenable signal valid state. This is used for RS-485 (half duplex) operation, to delay transmit data until the driver is enabled, allowing for driver enable delays, isolation barrier delays, etc. Delay is in units of ClockLow period. Bit 4:: FIFOError, it indicates that a host push has overflowed the FIFO (Mainly for driver debugging). Bit 5:: DriveEnableAuto, When set, enables Drive when any data is in FIFO or Xmit Shift register, removes drive when FIFO and Xmit shift register are empty. Bit 6:: DriveEnableBit, If DriveEnableAuto is 0, controls Drive (for software control of Xmit drive).

rx_mode is bit mask defined in the Hostmot2 regmap: Bit 0:: FalseStart bit Status, 1 = false start bit detected Bit 1 = OverRun Status, 1 = overrun condition detected (no valid stop bit) Bit 2:: RXMaskEnable, 1= enable RXMask for half duplex operation, 0 = ignore RXMask Bit 4 = FIFOError, indicates that a host read has attempted to read more data than available. (mainly for driver debugging) Bit 5:: LostDataError, indicates that data was received with no room in FIFO, therefore lost Bit 6:: RXMask, RO RXMASK status Bit 7:: FIFO Has Data

rx_mode and tx_mode registers are currently write-only. There should possibly be a get-status function.

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.

RETURN VALUE

Returns 0 on success and -1 on failure.

SEE ALSO

hm2_uart_send(3), hm2_uart_read(3)

See src/hal/drivers mesa_uart.comp for an example usage.