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python-itho-wpu/itho_i2c.py

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import fcntl
import io
import logging
import pigpio
import struct
import time
logger = logging.getLogger(__name__)
actions = {
"getnodeid": [0x90, 0xE0],
"getserial": [0x90, 0xE1],
"getdatatype": [0xA4, 0x00],
"getdatalog": [0xA4, 0x01],
"getsetting": [0xA4, 0x10],
}
class I2CRaw:
def __init__(self, address, bus):
I2C_SLAVE = 0x0703
self.fr = io.open(f"/dev/i2c-{bus}", "rb", buffering=0)
self.fw = io.open(f"/dev/i2c-{bus}", "wb", buffering=0)
fcntl.ioctl(self.fr, I2C_SLAVE, address)
fcntl.ioctl(self.fw, I2C_SLAVE, address)
def write_i2c_block_data(self, data):
if type(data) is not list:
return -1
data = bytearray(data)
self.fw.write(data)
return 0
def read_i2c_block_data(self, n_bytes):
data_raw = self.fr.read(n_bytes)
unpack_format = "B" * n_bytes
return list(struct.unpack(unpack_format, data_raw))
def close(self):
self.fr.close()
self.fw.close()
class I2CMaster:
def __init__(self, address, bus, queue):
self.i = I2CRaw(address=address, bus=bus)
self.queue = queue
def compose_request(self, action, identifier):
if action == "getsetting":
request = (
[0x80]
+ actions[action]
+ [0x04, 0x13] # read, length
+ [0x00, 0x00, 0x00, 0x00] # current
+ [0x00, 0x00, 0x00, 0x00] # min
+ [0x00, 0x00, 0x00, 0x00] # max
+ [0x00, 0x00, 0x00, 0x00] # step
+ [0x00, identifier, 0x00]
)
else:
# 0x80 = source, 0x04 = msg_type, 0x00 = length
request = [0x80] + actions[action] + [0x04, 0x00]
request.append(self.calculate_checksum(request))
return request
def calculate_checksum(self, request):
s = 0x82
for i in request:
s += i
checksum = 256 - (s % 256)
if checksum == 256:
checksum = 0
return checksum
def execute_action(self, action, identifier):
request = self.compose_request(action, identifier)
request_in_hex = [hex(c) for c in request]
logger.debug(f"Request: {request_in_hex}")
result = None
for i in range(0, 20):
logger.debug(f"Executing action: {action}")
self.i.write_i2c_block_data(request)
time.sleep(0.21)
logger.debug("Queue size: {}".format(self.queue.qsize()))
if self.queue.qsize() > 0:
result = self.queue.get()
break
if result is None:
logger.error("No valid result in 20 requests")
return result
def close(self):
self.i.close()
class I2CSlave:
def __init__(self, address, queue):
self.address = address
self.queue = queue
self.pi = pigpio.pi()
if not self.pi.connected:
logger.error("not pi.connected")
return
def set_callback(self):
logger.debug("set_callback()")
self.event_callback = self.pi.event_callback(pigpio.EVENT_BSC, self.callback)
self.pi.bsc_i2c(self.address)
def callback(self, id, tick):
logger.debug(f"callback({id}, {tick})")
s, b, d = self.pi.bsc_i2c(self.address)
result = None
if b:
logger.debug(f"Received {b} bytes! Status {s}")
result = [hex(c) for c in d]
logger.debug(f"Callback Response: {result}")
if self.is_checksum_valid(result) and self.is_length_valid(result):
self.queue.put(result)
else:
logger.debug(f"Received number of bytes was {b}")
def is_checksum_valid(self, b):
s = 0x80
for i in b[:-1]:
s += int(i, 0)
checksum = 256 - (s % 256)
if checksum == 256:
checksum = 0
if checksum != int(b[-1], 0):
logger.debug(f"Checksum invalid (0x{checksum:02x} != {b[-1]})")
return False
return True
def is_length_valid(self, b):
length_in_msg = int(b[4], 0)
actual_length = len(b) - 6
if length_in_msg != actual_length:
logger.debug(f"Length invalid ({length_in_msg} != {actual_length})")
return False
return True
def close(self):
self.event_callback.cancel()
self.pi.bsc_i2c(0)
self.pi.stop()