PRUserial485 - SIRIUS

PRU-based high performance serial communication

Author:
Patricia H. Nallin ( patricia.nallin@lnls.br )

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Building the library

Enter the folder src and run make install. This will compile PRU and host codes, install it to your Beaglebone and create a Python module to use these libraries.

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Using the library

Before using it

1. Apply the Device Tree Overlay (DTO) to configure Beaglebone pins to PRU. Run overlay.sh script each time you restart your Beaglebone.

2. In your python3 code, you can just:

import PRUserial485

It is not needed to copy any library files to your project.

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Available Methods

General Purpose

• PRUserial485_open(int baudrate, char mode)

  PRU initialization. Shared memory configuration and loading binaries into PRU.

  • baudrate:
    RS485 serial desired baudrate. Available: 9600, 14400, 19200, 38400, 57600, 115200 bps and 6, 10, 12 Mbps
  • mode:
    "M" for master and "S" for slave mode.

• PRUserial485_address()

  Gets SERIALxxCON board address (hardware defined) Returns: integer value (0 to 31)

• PRUserial485_close()

  Closes PRUs and memory mapping.

• PRUserial485_write(bytes, float timeout)

  Sending data through RS485 network

  Parameters

  • data:
    Python bytes containing values to be transmitted through serial network.
  • timeout:
    Maximum waiting time to start getting an answer, in milliseconds (ms). Minimum: 15ns / Maximum: 64s. If 0, does not wait for response. ATTENTION: in slave mode, this parameter is ignored.

  Return

  • MASTER MODE:
    Returns only after response received (valid response, timeout or ignored)
  • SLAVE MODE:
    Returns just after data completely sent.

• PRUserial485_read(uint32_t nbytes)

  Receiving data through RS485 network

  Parameters

  • nbytes (OPTIONAL):
    Number of bytes to read. If empty or 0, all data will be read. If nbytes is greater than available bytes, return all available bytes. Note: This function does not block or wait for incoming data.

  Return: bytes corresponding to data received.

• PRUserial485_read_flush()

  Flush receive FIFO buffer.

Curves

• PRUserial485_curve(int block, [float_list curve1, float_list curve2, float_list curve3, float_list curve4])

  Storing curves into memory. Each curve correspond to a power supply in the crate.

  Parameters

  • curveX:
    Python float list containing curve points, up to 6250 points. Curves must all have same length.
  • block:
    Identification of block which will be loaded with curve points. (0 to 3)

• PRUserial485_set_curve_block(int block)

  Selection of block which will be performed in next cycle. Default value is 0.

  Parameters

  • block:
    Identification of block (0 to 3)

• PRUserial485_read_curve_block()

  Read block identification which will be performed in next cycle.

  Returns: Block identification (0 to 3)

• PRUserial485_set_curve_pointer(int next_point)

  Selection of point of curve that will be performed after the next sync pulse

  Parameters

  • next_point:
    index of next point (0 to (len(curve)-1))

• PRUserial485_read_curve_pointer()

  Read curve index (point) which will be sent in next sync pulse.

  Returns: index of next point (0 to (len(curve)-1))

Sync Operation

• PRUserial485_sync_start(int sync_mode, float delay, int sync_address)

  Sync mode operation.

  Parameters

  • sync_mode:
    | 0x51 - Single curve sequence & Intercalated read messages
    | 0x5E - Single curve sequence & Read messages at End of curve
    | 0xC1 - Continuous curve sequence & Intercalated read messages
    | 0xCE - Continuous curve sequence & Read messages at End of curve
    | 0x5B - Single Sequence - Single Broadcast Function command
  • delay:
    time between end of sync serial message and start of a normal message, when sending normal commands after sync pulses.
  • sync_address:
    PS Controller address to which setpoints will be addressed to. Parameter only needed if sync_mode != 0x5B

• PRUserial485_sync_stop()

  Stops sync operation mode.

• PRUserial485_sync_status()

  Verifies whether PRU is waiting for a sync pulse or not

  Returns: 1 if true, 0 if false

• PRUserial485_read_pulse_count_sync()

  Read number of sync pulses already received.

  Returns: counting value (0 to (2^32 - 1))

• PRUserial485_clear_pulse_count_sync()

  Clears pulse counting registers. Action is only performed if sync mode is disabled.