OVMS3-idf/tools/tiny-test-fw/Utility/Attenuator.py
2018-10-24 11:20:54 +02:00

71 lines
1.9 KiB
Python

# Copyright 2015-2017 Espressif Systems (Shanghai) PTE LTD
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http:#www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
Internal use only.
This file provide method to control programmable attenuator.
"""
import time
import serial
import codecs
def set_att(port, att, att_fix=False):
"""
set attenuation value on the attenuator
:param port: serial port for attenuator
:param att: attenuation value we want to set
:param att_fix: fix the deviation with experience value
:return: True or False
"""
assert 0 <= att <= 62
# fix att
if att_fix:
if att >= 33 and (att - 30 + 1) % 4 == 0:
att_t = att - 1
elif att >= 33 and (att - 30) % 4 == 0:
att_t = att + 1
else:
att_t = att
else:
att_t = att
serial_port = serial.Serial(port, baudrate=9600, rtscts=False, timeout=0.1)
if serial_port.isOpen() is False:
raise IOError("attenuator control, failed to open att port")
cmd_hex = "7e7e10{:02x}{:x}".format(att_t, 0x10 + att_t)
exp_res_hex = "7e7e20{:02x}00{:x}".format(att_t, 0x20 + att_t)
cmd = codecs.decode(cmd_hex, "hex")
exp_res = codecs.decode(exp_res_hex, "hex")
serial_port.write(cmd)
res = b""
for i in range(5):
res += serial_port.read(20)
if res == exp_res:
result = True
break
time.sleep(0.1)
else:
result = False
serial_port.close()
return result