rmi-power.py

#!/usr/bin/python3

import usb.core
import usb.util
import struct

CLINK_USB_PID = 0x1b1c
CLINK_USB_VIP = 0x1c0c

CLINK_GET_PRODUCT = (0x03, 0x9a) + (0,)*(64 - 2)
CLINK_GET_POWER = (0x03, 0xee) + (0,)*(64 - 2)
CLINK_GET_INPUT = (0x03, 0x88) + (0,)*(64 - 2)

def array_to_float(arr):
  if len(arr) != 2:
    raise ValueError("Length must be 2")

  int16 = (arr[1] << 8) | arr[0]
  exponent = int16 >> 11
  fraction = int16 & 2047

  if exponent > 15:
    exponent = -(32 - exponent)
  if fraction > 1023:
    fraction = -(2048 - fraction)
  if (fraction & 1) == 1:
    fraction += 1
    
  return float(fraction) * pow(2.0, float(exponent))

def request_value(name):
  ep_write.write(name)
  read_buf = ep_read.read(64)
  return array_to_float(read_buf[2:4])

def request_string(name):
  ep_write.write(name)
  read_buf = ep_read.read(64)
  return "".join([chr(n) for n in read_buf[2:]]).strip()

# find our device
dev = usb.core.find(idVendor=CLINK_USB_PID, idProduct=CLINK_USB_VIP)

if dev.is_kernel_driver_active(0):
  print('Kernel driver was active, detaching')
  dev.detach_kernel_driver(0)

# was it found?
if dev is None:
  raise ValueError('Device not found')

# set the active configuration. With no arguments, the first
# configuration will be the active one
dev.set_configuration()

# get an endpoint instance
cfg = dev.get_active_configuration()
intf = cfg[(0,0)]

ep_read = usb.util.find_descriptor(
  intf,
  # match the first OUT endpoint
  custom_match = \
  lambda e: \
    usb.util.endpoint_direction(e.bEndpointAddress) == \
    usb.util.ENDPOINT_IN)

ep_write = usb.util.find_descriptor(
  intf,
  # match the first OUT endpoint
  custom_match = \
  lambda e: \
    usb.util.endpoint_direction(e.bEndpointAddress) == \
    usb.util.ENDPOINT_OUT)

assert ep_read is not None
assert ep_write is not None

product = request_string(CLINK_GET_PRODUCT)
print('Device: {}'.format(product))

output_power = request_value(CLINK_GET_POWER)
input_voltage = request_value(CLINK_GET_INPUT)

print('Input: {}V'.format(input_voltage))

power_sq = output_power ** 2
# Only for RM850i
if 'RM850i' in product:
  input_power = (0.0001282672 * power_sq + 1.015599 * output_power + 12.41156) if (input_voltage < 180.0) else (7.752753E-05 * power_sq + 1.030425 * output_power + 9.844185)

  print('Input Power: {:.2f}W'.format(input_power))
  print('Efficiency: {:.2f}%'.format(output_power*100/input_power))

print('Output Power: {:.2f}W'.format(output_power))