phaser/LEDs: add global getter and individual getter/setter helpers

[airwoodix]

ARTIQ Pull Request

Description of Changes

Add convenience methods to Phaser coredevice driver for manipulating front panel LEDs.

New methods:

• get_leds(): retrieve the state of all front panel LEDs on 6 bits
• set_led(index, state): change the state of a single front panel LED
• get_led(index): get the state of a single front panel LED

get_leds() includes some slack to compensate for the register delay.

Testing:

The LED wave code in artiq_sinara_tester is simpler with the existing set_leds() method (no modification). This patch was tested manually with the following snippet:

from artiq.experiment import *


class PhaserLEDs(EnvExperiment):
    def build(self):
        self.setattr_device("core")
        self.setattr_device("phaser0")

    @kernel
    def run(self):
        self.core.reset()

        # red LEDs on
        self.phaser0.set_leds(0b101011)
        assert self.phaser0.get_leds() == 0b101011
        delay(1 * s)

        # LED wave
        for _ in range(5):
            for led in range(6):
                for state in [True, False]:
                    self.phaser0.set_led(led, state)
                    assert self.phaser0.get_led(led) is state
                    delay(100 * ms)

Type of Changes

	Type
	🐛 Bug fix
✓	✨ New feature
	🔨 Refactoring
	📜 Docs

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Licensing

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ARTIQ files that do not contain a license header are copyrighted by M-Labs Limited and are licensed under LGPLv3+.

[sbourdeauducq]

Looks arbitrary and other drivers e.g. TTL, Sampler do not integrate such slack.

[sbourdeauducq]

This is not consistent with Zotino, which does not have such functions.
https://github.com/m-labs/artiq/blob/master/artiq/coredevice/zotino.py#L45