|
| 1 | +""" |
| 2 | +This module implements the communication protocol to switch the digital outputs |
| 3 | +on a Denkovi USB Relay. |
| 4 | +
|
| 5 | +Supported Functionality: |
| 6 | +
|
| 7 | +- Turn digital output on and off |
| 8 | +""" |
| 9 | + |
| 10 | +import usb.core |
| 11 | +import usb.util |
| 12 | + |
| 13 | +from pylibftdi import BitBangDevice |
| 14 | +from threading import Lock |
| 15 | + |
| 16 | + |
| 17 | +class DenkoviRelay: |
| 18 | + lock = Lock() |
| 19 | + |
| 20 | + def __init__(self, **args): |
| 21 | + self._dev = usb.core.find(**args) |
| 22 | + |
| 23 | + if self._dev is None: |
| 24 | + raise ValueError("Device not found") |
| 25 | + |
| 26 | + self._serialNumber = usb.util.get_string(self._dev, self._dev.iSerialNumber) |
| 27 | + |
| 28 | + if self._serialNumber is None: |
| 29 | + raise ValueError("Failed to get device serial number") |
| 30 | + |
| 31 | + self.lock.acquire() |
| 32 | + |
| 33 | + bitbangDev = BitBangDevice(self._serialNumber) |
| 34 | + |
| 35 | + if bitbangDev is None: |
| 36 | + raise ValueError("Failed to instantiate bitbang device") |
| 37 | + |
| 38 | + bitbangDev.direction = 0xFF |
| 39 | + |
| 40 | + bitbangDev.close() |
| 41 | + |
| 42 | + self.lock.release() |
| 43 | + |
| 44 | + def set_output(self, number, status): |
| 45 | + assert 1 <= number <= 8 |
| 46 | + number = number - 1 |
| 47 | + |
| 48 | + self.lock.acquire() |
| 49 | + |
| 50 | + bitbangDev = BitBangDevice(self._serialNumber) |
| 51 | + |
| 52 | + if bitbangDev is None: |
| 53 | + raise ValueError("Failed to instantiate bitbang device") |
| 54 | + |
| 55 | + if status: |
| 56 | + bitbangDev.port = bitbangDev.port | (1 << number) |
| 57 | + else: |
| 58 | + bitbangDev.port = bitbangDev.port & ~(1 << number) |
| 59 | + |
| 60 | + bitbangDev.close() |
| 61 | + |
| 62 | + self.lock.release() |
| 63 | + |
| 64 | + def get_output(self, number): |
| 65 | + assert 1 <= number <= 8 |
| 66 | + number = number - 1 |
| 67 | + |
| 68 | + val = None |
| 69 | + |
| 70 | + self.lock.acquire() |
| 71 | + |
| 72 | + bitbangDev = BitBangDevice(self._serialNumber) |
| 73 | + |
| 74 | + if bitbangDev is None: |
| 75 | + raise ValueError("Failed to instantiate bitbang device") |
| 76 | + |
| 77 | + if bitbangDev.port & (1 << number): |
| 78 | + val = True |
| 79 | + else: |
| 80 | + val = False |
| 81 | + |
| 82 | + bitbangDev.close() |
| 83 | + |
| 84 | + self.lock.release() |
| 85 | + |
| 86 | + return val |
| 87 | + |
| 88 | + def __del__(self): |
| 89 | + usb.util.release_interface(self._dev, 0) |
| 90 | + |
| 91 | + |
| 92 | +_relays = {} |
| 93 | + |
| 94 | + |
| 95 | +def _get_relay(busnum, devnum): |
| 96 | + if (busnum, devnum) not in _relays: |
| 97 | + _relays[(busnum, devnum)] = DenkoviRelay(bus=busnum, address=devnum) |
| 98 | + return _relays[(busnum, devnum)] |
| 99 | + |
| 100 | + |
| 101 | +def handle_set(busnum, devnum, number, status): |
| 102 | + relay = _get_relay(busnum, devnum) |
| 103 | + relay.set_output(number, status) |
| 104 | + |
| 105 | + |
| 106 | +def handle_get(busnum, devnum, number): |
| 107 | + relay = _get_relay(busnum, devnum) |
| 108 | + return relay.get_output(number) |
| 109 | + |
| 110 | + |
| 111 | +methods = { |
| 112 | + "set": handle_set, |
| 113 | + "get": handle_get, |
| 114 | +} |
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