PLUTO_SERVO

pluto_servo − Hardware driver and firmware for the Pluto-P parallel-port FPGA, for use with servo machines.

loadrt pluto_servo [ioaddr=N] [ioaddr_hi=N] [epp_wide=N] [watchdog=N] [test_encoder=N]

ioaddr [default: 0x378]

The base address of the parallel port.

ioaddr_hi [default: 0]

The secondary address of the parallel port, used to set EPP mode. 0 means to use ioaddr + 0x400. -1 means there is no secondary address. The secondary address is used to set the port to EPP mode.

epp_wide [default: 1]

Set to zero to disable the "wide EPP mode". "Wide" mode allows a 16- and 32-bit EPP transfers, which can reduce the time spent in the read and write functions. However, this may not work on all EPP parallel ports.

watchdog [default: 1]

Set to zero to disable the "hardware watchdog". "Watchdog" will tristate all outputs approximately 6ms after the last execution of pluto-servo.write, which adds some protection in the case of emc crashes.

test_encoder [default: 0]

Internally connect dout0..2 to QA0, QB0, QZ0 to test quadrature counting

Pluto_servo is an emc2 software driver and associated firmware that allow the Pluto-P board to be used to control a servo-based CNC machine.

The driver has 4 PWM channels, 4 quadrature channels with index pulse, 18 digital outputs (8 shared with PWM), and 20 digital inputs (12 shared with quadrature).

Encoders

The encoder pins and parameters conform to the ‘canonical encoder’ interface described in the HAL manual. It operates in ‘x4 mode’.

The sample rate of the encoder is 40MHz. The maximum number quadrature rate is 8191 counts per emc2 servo cycle. For correct handling of the index pulse, the number of encoder counts per revolution must be less than 8191.

PWM

The PWM pins and parameters conform to the ‘canonical analog output’ interface described in the HAL manual. The output pins are ‘up/down’ or ‘pwm/dir’ pins as described in the documentation of the ‘pwmgen’ component.

Internally the PWM generator is based on a 12-bit, 40MHz counter, giving 4095 duty cycles from -100% to +100% and a frequency of approximately 19.5kHz. In PDM mode, the duty periods are approximately 100ns long.

Digital I/O

The digital output pins conform to the ‘canonical digital output’ interface described in the HAL manual.

The digital input pins conform to the ‘canonical digital input’ interface described in the HAL manual.

pluto-servo.read (uses floating-point)

Read all the inputs from the pluto-servo board

pluto-servo.write (uses floating-point)

Write all the outputs on the pluto-servo board

pluto-servo.encoder.M.count s32 out (M=0..3)

pluto-servo.encoder.M.position float out (M=0..3)

pluto-servo.encoder.M.velocity float out (M=0..3)

pluto-servo.encoder.M.reset bit in (M=0..3)

pluto-servo.encoder.M.index-enable bit io (M=0..3)

encoder.M corresponds to the pins labeled QAM, QBM, and QZM on the pinout diagram

pluto-servo.pwm.M.value float in (M=0..3)

pluto-servo.pwm.M.enable bit in (M=0..3)

pwm.M corresponds to the pins labeled UPM and DNM on the pinout diagram

pluto-servo.dout.MM bit in (MM=00..19)

dout.0M corresponds to the pin labeled OUTM on the pinout diagram. Other pins are shared with the PWM function, as follows:

Pin

Shared

Label

with

dout.10

UP0

dout.10

UP0

dout.12

UP1

dout.14

UP2

dout.18

UP3

dout.11

DOWN0

dout.13

DOWN1

dout.15

DOWN2

dout.19

DOWN3

pluto-servo.din.MM bit out (MM=00..19)

pluto-servo.din.MM-not bit out (MM=00..19)

For M=0 through 7, din.0M corresponds to the pin labeled INM on the pinout diagram. Other pins are shared with the encoder function, as follows:

Pin

Shared

Label

with

din.8

QZ0

din.9

QZ1

din.10

QZ2

din.11

QZ3

din.12

QB0

din.13

QB1

din.14

QB2

din.15

QB3

din.16

QA0

din.17

QA1

din.18

QA2

din.19

QA3

pluto-servo.encoder.M.scale float rw (M=0..3) (default: 1)

pluto-servo.encoder.z-polarity bit rw

Set to TRUE if the index pulse is active low, FALSE if it is active high. Affects all encoders.

pluto-servo.pwm.M.offset float rw (M=0..3)

pluto-servo.pwm.M.scale float rw (M=0..3) (default: 1)

pluto-servo.pwm.M.max-dc float rw (M=0..3) (default: 1)

pluto-servo.pwm.M.min-dc float rw (M=0..3) (default: 0)

pluto-servo.pwm.M.pwmdir bit rw (M=0..3) (default: 0)

Set to TRUE use PWM+direction mode. Set to FALSE to use Up/Down mode.

pluto-servo.pwm.is-pdm bit rw

Set to TRUE to use PDM (also called interleaved PWM) mode. Set to FALSE to use traditional PWM mode. Affects all PWM outputs.

pluto-servo.dout.MM-invert bit rw (MM=00..19)

If TRUE, the output on the corresponding dout.MM is inverted.

pluto-servo.communication-error u32 rw

Incremented each time pluto-servo.read detects an error code in the EPP status register. While this register is nonzero, new values are not being written to the Pluto-P board, and the status of digital outputs and the PWM duty cycle of the PWM outputs will remain unchanged. If the watchdog is enabled, it will activate soon after the communication error is detected. To continue after a communication error, set this parameter back to zero.

pluto-servo.debug-0 s32 rw

pluto-servo.debug-1 s32 rw

These parameters can display values which are useful to developers or for debugging the driver and firmware. They are not useful for integrators or users.

The pluto_servo section in the HAL User Manual, which shows the location of each physical pin on the pluto board.

GPL