plate_io.py

import sys
import json
import piplates.DAQCplate as DP
import piplates.DAQC2plate as DP2
import piplates.RELAYplate as RP
import piplates.MOTORplate as MP
import simpleflock

# All Pi Plate communication must go through this one process to ensure
# SPI communications don't overlap / interfere and corrupt the device state(s)
#
# listen for json messages on stdin of the format:
# {
#   addr: <pi plate address 0-7>,
#   plate_type: <RELAY|DAQC>,
#   cmd: <command string>, args: {<command-specific args>}
# }

#TODO: scan for plates at startup so we can handle wrong-address
#      or plate_type mismatch exceptions

while True:
    try:
        line = sys.stdin.readline()
        # TODO: add error handling for invalid JSON
        msg = json.loads(line)
        addr = msg['addr']
        plate_type = msg['plate_type']
        cmd = msg['cmd']
        args = msg['args']
        resp = {}
        if (plate_type == "RELAY"):
            with simpleflock.SimpleFlock("/tmp/relay.lock", timeout = 3):
                if (cmd == "setLED"):
                    RP.setLED(addr)
                    resp['LED'] = 1
                elif (cmd == "clrLED"):
                    RP.clrLED(addr)
                    resp['LED'] = 0
                elif (cmd == "toggleLED"):
                    RP.toggleLED(addr)
                    resp['LED'] = "UNKNOWN"
                elif (cmd == "getID"):
                    resp['ID'] = RP.getID(addr)
                elif (cmd == "getHWrev"):
                    resp['HWrev'] = RP.getHWrev(addr)
                elif (cmd == "getFWrev"):
                    resp['FWrev'] = RP.getFWrev(addr)
                elif (cmd == "getPMrev"):
                    resp['PMrev'] = RP.getPMrev()
                elif (cmd == "getADDR"):
                    resp['ADDR'] = RP.getADDR(addr)
                elif ("relay" in cmd):
                    relay = args['relay']
                    if (cmd == "relayON"):
                        RP.relayON(addr, relay)
                    elif (cmd == "relayOFF"):
                        RP.relayOFF(addr, relay)
                    elif (cmd == "relayTOGGLE"):
                        RP.relayTOGGLE(addr, relay)
                    state = RP.relaySTATE(addr)
                    this_state = (state >> (relay - 1)) & 1
                    resp['relay'] = relay
                    resp['state'] = this_state
                elif (cmd == "RESET"):
                    RP.RESET(addr)
                    resp['RESET'] = "OK";
                else:
                    sys.stderr.write("unknown relay cmd: " + cmd)
                    break
                print(json.dumps(resp))
        elif (plate_type == "DAQC"):
            with simpleflock.SimpleFlock("/tmp/daqc.lock", timeout = 3):
                if (cmd == "getDINbit"):
                    bit = args['bit']
                    try:
                        state = DP.getDINbit(addr, bit)
                    except AssertionError:
                        state = DP2.getDINbit(addr,bit)
                    resp['bit'] = bit
                    resp['state'] = state
                elif (cmd == "setDOUTbit"):
                    bit = args['bit']
                    try:
                        DP.setDOUTbit(addr, bit)
                    except AssertionError:
                        DP2.setDOUTbit(addr, bit)
                    resp['bit'] = bit
                    resp['state'] = 1
                elif (cmd == "clrDOUTbit"):
                    bit = args['bit']
                    try:
                        DP.clrDOUTbit(addr, bit)
                    except AssertionError:
                        DP2.clrDOUTbit(addr, bit)
                    resp['bit'] = bit
                    resp['state'] = 0
                elif (cmd == "toggleDOUTbit"):
                    bit = args['bit']
                    try:
                        DP.toggleDOUTbit(addr, bit)
                    except AssertionError:
                        DP2.toggleDOUTbit(addr, bit)
                    resp['bit'] = bit
                    resp['state'] = 'UNKNOWN'
                elif (cmd == "getADC"):
                    channel = args['channel']
                    try:
                        voltage = DP.getADC(addr, channel)
                    except AssertionError:
                        voltage = DP2.getADC(addr, channel)
                    resp['channel'] = channel
                    resp['voltage'] = voltage
                elif (cmd == "getTEMP"):
                    bit = args['bit']
                    scale = args['scale']
                    try:
                        temp = DP.getTEMP(addr, bit, scale)
                    except AssertionError:
                        temp = DP2.getTEMP(addr, bit, scale)
                    resp['temp'] = temp
                    resp['bit'] = bit
                else:
                    sys.stderr.write("unknown daqc cmd: " + cmd)
                print(json.dumps(resp))
        elif (plate_type == "MOTOR"):
            break
        else:
            sys.stderr.write("unknown plate_type: " + plate_type)
    except (EOFError, SystemExit):
        sys.exit(0)