MicroPython
SIM7600 library for micropython #11649
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Hi. I am using MicroPython on a RP2040 and have a SIM7600 board attached. I have an existing project which monitors some sensors and sets off a buzzer, etc if a sensor is out of range. The project uses asyncio. I would like to add sending and receiving SMS messages to this project. Is there a library available that will let me do that? Thank you! |
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Replies: 13 comments 18 replies
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use AT commands via UART between rp2040 and module. All AT command you have in product description, so from RP side you have to |
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Hi... Thank you for the link and suggestion :-) I am using the class SIM_UART code as a class, and calling it from my main file async def sms_loop(): The first problem I face is I can't seem to find a link to the pyb library (from pyb import UART) - so instead I am using (from machine import UART, Pin) - and this is I think working - and this lets me define the Tx/Rx pins. I am using a RP2040 board. And secondly (and I am sure I am doing something quite wrong here) I need to send the AT command twice to send a SMS - and the format is not as I expected - but it does send a SMS :-) The first time I send res = await sim_uart.send_command('AT+CMGS="+6421123456"\rHello User\x1A') it does not send a SMS, and I see in the log (the ? in black here is actually a square box in the log...): If I then run the exact same command a second time, I actually receive a SMS and see this in the log: The SMS when received on my phone looks like this: I guess I have the format here incorrect? How do I use the number, but only send the actual text message 'Hello User'? Thanks for any help! |
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The I have updated it to assume an RP2. The from machine import UART
import uasyncio as asyncio
from primitives import Delay_ms
class SIM_UART():
def __init__(self, timeout=4000):
self.uart = UART(0, 9600, rx=Pin(1, Pin.IN), tx=Pin(0, Pin.OUT))
self.timeout = timeout
self.swriter = asyncio.StreamWriter(self.uart, {})
self.sreader = asyncio.StreamReader(self.uart)
self.delay = Delay_ms()
self.response = []
asyncio.create_task(self.recv())
async def recv(self):
while True:
res = await self.sreader.readline()
self.response.append(res) # Append to list of lines
self.delay.trigger(self.timeout) # Got something, retrigger timer
async def send_command(self, command):
self.response = [] # Discard any pending messages
await self.swriter.awrite("{}\r\n".format(command))
print("<", command)
self.delay.trigger(self.timeout) # Re-initialise timer
await self.delay.wait() # Wait for 4s after last msg received
return b''.join(self.response)
async def test():
res = await sim_uart.send_command('rats')
if res:
print('Result is:' , res)
else:
print('Timed out waiting for result.')
sim_uart = SIM_UART()
try:
asyncio.run(test())
finally:
_ = asyncio.new_event_loop() |
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Hi Peter Thank you. Running your latest code - I needed to make two changes for the SIM7600 - baud rate 115200 and a timeout added to the same line, and I am sending: Unfortunately the same issue as previously. First time running no SMS is sent and I get: |
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Before sending SMS message , put some commands for status checking like: , sim status registration checking/ enabling status; SMS message config etc. Im not sure (it is my interpretation), but it look like at the first attempt of sending sms modem accept only phone number, and with the second attempt rest of command ? (send_command() has all ready ( \r) , but try modify and add ("\r" ) and ( "1A" ) manually in commands. |
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@andypnz I can help with My general approach to this type of problem would be to connect a terminal program to the device and learn how to drive it manually. Then modify the code to match. |
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Thank you @peterhinch @2dof (sorry about the formatting below! Trying to sort out) My problem now is although it correctly sends a SMS, it crashes with the error below. I think an issue in async def recv(self) ? |
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I think the problem here is that the UART is timing out. Try setting the timeouts to a very long value: self.uart = UART(0, 115200, rx=Pin(1, Pin.IN), tx=Pin(0, Pin.OUT), timeout=1000_000, timeout_char=1000_000) |
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Hi Peter |
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does error occur when You send sms like I suggested (i.e) put commands, message separately ? if yes , note that between sending command. message delay should be small (for example 100 ms ). when send module should return (after 4-5 sec) some status/confirmation code in format +CMGS: . mr : number . code error |
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Iss #8344 was fixed. |
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@2dof Thank you for the suggestion - I have tried various delays with no change in behavior.... |
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@andypnz I'm not clear what you're seeing. With my suggested value of 1,000,000 the timeout should be 1,000s or about 16.6 minutes. Please let me know how long it actually takes to fail. FYI I raised #10867 in February as UART timeouts keep causing |
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@peterhinch With the 1,000,000 timeout, it delays the 'Timed out waiting for result.' and 'Task exception wasn't retrieved' errors by maybe 10 seconds. With the 1,000,000 timeout, and my code changed to send 2 x SMS's: |
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I also tried using a ESP32 - 2 x SMS send with the same timeout issue, but the big error list happens much sooner: |
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Taking a step backwards - it I only send 'AT' as the command, this is the result. Each command returns a result, but with errors between - except the first which returns with no error. |
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Sadly the Pico UART isn't working properly, and is timing out far too early. This can be proved by pasting the following (link pins 0 and 1): from machine import UART, Pin
uart = UART(0, 115200, rx=Pin(1, Pin.IN), tx=Pin(0, Pin.OUT), timeout=1000_000, timeout_char=1000_000)
uart.readline()Times out after 15s rather than 16.6mins. I have raised an issue #11678. |
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I tried the same test on a ESP32 and a Nucleo L476RG - with the same result - times out after around 15s..... I guess I need to await this issue to be solved prior to trying to debug this? Please let me know if you hear anything :-) |
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I think the best that can be done is to do uart = UART(0, 115200, rx=Pin(1, Pin.IN), tx=Pin(0, Pin.OUT), timeout=65535, timeout_char=65535)which gives a timeout of 1min 5.5s. Then create a task which sends an AT command every (say) 50s. Clearly you need to send something harmless that merely triggers the modem into sending a response and stopping the receiver from timing out. The receive loop then recognises and discards the "harmless" response. |
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Hi Peter. Unfortunately I don't think I have implemented your suggestion correctly. This code does not send any SMS, and errors as below: class_sim_800.py: and a list of similar errors..........` |
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If I leave out the at_sms_loop, I get sent the 2 x SMS's, but then eventually crashes as we know |
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It seems that the timeout variable is 16 bit in each and every port I looked into. So the largest reasonable value is 65535 at the moment. |
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@peterhinch Peter - Do you think you would have time to try and solve this for the community if I sent you a SIM7600 (to keep)? I don't have the skills here, and I do think this would be a useful library to have (and be working with uasyncio)? |
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Thanks for the offer but I'm not in a position to take this on as a project, but I will help with the The following makes use of the timeout feature which is new to from machine import UART, Pin
import uasyncio as asyncio
from primitives import Delay_ms
class SIM_UART():
def __init__(self):
self.uart = UART(0, 115200, rx=Pin(1, Pin.IN), tx=Pin(0, Pin.OUT), timeout=65_535, timeout_char=65_535)
while self.uart.any():
self.uart.read(1) # Clear any initial garbage
self.swriter = asyncio.StreamWriter(self.uart, {})
self.sreader = asyncio.StreamReader(self.uart)
self.delay = Delay_ms(duration=40_000) # 40s (less than UART timeouts)
self.lock = asyncio.Lock()
asyncio.create_task(self.keep_alive())
async def keep_alive(self):
while True:
await self.delay.wait()
self.delay.clear()
res = await self.send_command("AT")
if not res:
raise OSError("Modem not responding")
async def send_command(self, command):
res = b""
async with self.lock: # Don't allow concurrent messages
await self.swriter.awrite(f"{command}\r\n")
done = False
while not done:
try:
r = await asyncio.wait_for(self.sreader.readline(), 4)
self.delay.trigger()
res = b"".join((res, r))
except asyncio.TimeoutError:
done = True # No more data from device
return res
async def test():
res = await sim_uart.send_command('AT')
if res:
print('Result is:' , res)
else:
print('Timed out waiting for result.')
await asyncio.sleep(120) # Test keep_alive
sim_uart = SIM_UART()
try:
asyncio.run(test())
finally:
_ = asyncio.new_event_loop()
# await sim_uart.send_command("AT+CMGS=13012832788") # Phone no.
# await sim_uart.send_command("hello\x1B") # Terminate with ESC (0x1B) or ctrl-z (0x1A)The final comments are my guess at what is needed to send an SMS. The manual indicates that the text must be terminated with |
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Hi @peterhinch Peter |
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The My memory of driving modems with AT strings is flaky: I last did it in the days of dial-up internet. |
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Hi Peter Ok, I think the problem is the keep alive AT command is not synchronized with sending a message. So the keep alive AT command ends up in the message string - and appears on my phone. There is no AT command possible that does not have a response of some sort. If I remove the keep alive AT command from the class, and instead send some 'keep alive' AT commands within async def test(): (and therefore coordinated with sending an actual SMS) all works as expected. It is almost like we need a flag to only send a keep alive AT command if there is no SMS about to be sent? Is that what you would think? What would be the best implementation? And finally to receive a SMS from my phone - I guess the thing to do is to keep checking the modem for new messages on a regular basis (say every 0.5 sec) using the get unread message AT command? Thank you! |
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If you are going to regularly poll the device for incoming SMS that would indeed keep the UART receiver alive. You would still need synchronisation to ensure that your polling did not occur while you were sending an SMS, otherwise you would get the same problem as you have now. Evidently my synchronisation isn't working. I'll explain how it's supposed to work, and maybe one of us will spot the flaw. Firstly the Reception of a line retriggers the The 4s timeout does assume that the modem responds to a command within 4s and then remains silent until it gets another command. If it sends unsolicited messages or pauses for >4s between lines, then the extra data will be stored in the modem receive buffer causing the next |
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One thing you could try is to amend the async def send_command(self, command):
res = b""
uns = b""
async with self.lock: # Don't allow concurrent messages
# Collect and print any unsolicited messages
done = False
while not done:
try:
r = await asyncio.wait_for(self.sreader.readline(), 1)
uns = b"".join((uns, r))
except asyncio.TimeoutError:
done = True # No more data from device
if uns:
print(f"Unsolicited: {uns}")
# UART buffer is now empty: send the command and await the response
await self.swriter.awrite(f"{command}\r\n")
done = False
while not done:
try:
r = await asyncio.wait_for(self.sreader.readline(), 4)
self.delay.trigger()
res = b"".join((res, r))
except asyncio.TimeoutError:
done = True # No more data from device
return resThis will report any unsolicited messages or responses to the prior message that occurred after the 4s timeout had elapsed. |
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Hi Peter Thanks again! I will look at this more in the light of day tomorrow.... This occurred with your new send_command (but without using your keep alive loop) and me sending a receive unread request every 10 seconds with flags so nothing gets sent more frequently than every 10 seconds. I will also try with your full code tomorrow. Overall everything is working (I just need to parse out the message bit of the received message) - just this (I think unexpected) 'unsolicited'. Hope you are having a good weekend |
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Hi Peter Unfortunately no real progress. Try as I might I am unable to give a concise analysis of the cause for the 'unsolicited' responses. Fortunately these don't seem to have an impact on the functionality - which is working as expected. Rather than parsing the messages, I am using string.find() as I am just looking for a command to execute. And I use the same technique to check the phone number the message is from matches my white list. And confirming the phone number is present in the message means I only note an unknown command which is real. When I have some time I may put an analyser on the data stream and see if I can figure out a bit more. Thanks again for all your help :-) |
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Thanks for the offer but I'm not in a position to take this on as a project, but I will help with the
uasyncioand UART code. You'll need to research the AT codes.The following makes use of the timeout feature which is new to
uasyncioV3. I have tested it with a loopback. It solves the UART timeout problem by periodically (40 sec intervals) sending "AT" to the modem. As I understand it, this will cause it to respond and will keep the UART receiver alive. Thesend_commandmethod waits 4s to gather any response from the modem.