First of all, if there is a specific Stack Exchange for this topic please refer me to there.
I installed Micropython in a NodeMCU machine, connected via Tera Term and got garbage. I re-flashed the thing with the -fm dio argument (from some forum) and connected via Tera Term and I receive proper characters BUT when I type in I see garbage. And when I execute commands I see garbage too. Weird enough the NUMBERS are ok, just the letters change. It sounds like an ASCII problem not a communication problem...
To make things just weirder I closed the connection and opened it again and from time to time it works as expected. I was able to run the wifi setup (my PC has no wifi so it was useless but I wanted to try something meaningful).
And to make it even funnier Putty (the program I like to use all the time) does not work at all, even when replicating all the settings from Tera Term, it just refuses to connect to the thing.
Any clues?
Turn off VT100 emulation
I just ran into the same thing, and finally solved it after an hour of banging my head on it. For me numbers would work, as would most special characters and uppercase letters, but lowercase letters would come out as extended ascii symbols.
Related
I recently bought a modem that supports CSD (Circuit Switched Data) calls. I put SIM card in it and I am able to make calls via AT commands. But these are always VOICE calls. I have another modem and I need to connect to it via CSD.
I know it is possible because our colleagues are using it this way to access some network.
They are using windows dial-up connection, but I guess that is just something that in the background calls the AT commands.
Nevertheless the dial-up is still giving me "Error 678: Remote computer did not respond". I have tried many settings, but still the same error. I even tried different computer and still got the same error.
So I found out that when I call CSD, then on the receiving side (if AT+CRC=1) it should display +CRING: REL ASYNC. So I setup another modem and called it and it showed +CRING: VOICE.
So how do I convince my modem to call in the REL ASYNC mode?
I already tried:
AT+IPR=115200 or AT+IPR=9600
AT+FCLASS=0 (this is default though)
AT+CSNS=4
AT+CBST=7,0,0 or AT+CBST=71,0,1
AT^SXRAT=0 (this changes the network to GSM)
But still when I do ATDNUMBERIWANTTOCALL; the receiving side shows +CRING: VOICE.
Also my mobile provider ensured me, that the CSD technology is still supported in my country and that I do not need any kind of special SIM card.
You need to remove the semicolon after the phone number in the ATD command: that semicolon is what tells the modem to make a voice call rather than CSD.
Check with your teleoperator does your sim card have separate data number.
Sometimes postpaid (and/or M2M) cards have three different numbers
1. voice
2. fax
3. data
In the end the number could be called normally like it is written in the question, but it only worked in Germany, not abroad...
I'm working with 2 little machines with limited unix tools. Both are conected between each other via serial. I'm transfering binary data, so the devices are on raw mode. The sending machine is sending files to the other one and between there's a delay of X ms (specified as parameter). I would like to know if it's possible to measure those delays on destination machine in order to identify how many files are coming. Till now i was using cat < /dev/ttyS5, but this is not a option to my purpose.
Any idea?
Thanks
IMHO the easiest way is to write a little program which is waiting for bytes on the serial line.
Everytime a character arrives some sort of timer/timestamp is reset.
Another thread could be evaluation this timer/timestamp in a loop and increment a counter if it's larger than a defined value.
But please be aware that you might experience delays from the serial line as there's the kernel and its scheduler "in between". Furthermore you'll need appropriate locking of course!
Folks
I have two protoypes (say prototype A and B ). Both the prototypes uses Telit GSM modem .
I am using the common SIM to work with both of them.
Problem: If I use the sim with prototype A , AT+CGDCONT, AT#GPRS=1 these commands work perfect . But with Prototype B using the same sim AT+CGDCONT, AT#GPRS=1 don't work .
AT+CGDCONT always echos "operation not allowed" .
So is there any way i can debug this issue ?
Thanks
Ak
You might want to ramp up the error detail. Try setting:
AT+CMEE=1
Most common GSM Modems with a standard AT Command set will then output proper error codes. I have found often such generic messages are then replaced with much more detailed error codes.
Swap the GSM modems and see if the fault moves with the swap. If it does, dump the faulty modem (i.e. replace it to see if that cures the problem). If not the problem may be with your prototype.
It is difficult to guess the reasons. It could be that module B is faulty.
Even though you think both devices are identical, there are settings that might make them different. I remember Telit have commands like AT#SELINT and you have to check whether those settings are the same for both modules. There are a couple of other settings like this which persists after power cycles. If you don't know how to track those differences, you can always format the modules.
Go to Roundsolutions Download section and download the firmware for the module and burn them in using the tools in the same website. After that is done, you will be sure that they are really identical.
A bit of history: We have an application, which was originally written many years ago (1998 is the first date in PVCS but the app is about 5 years older than that as it originally was a DOS program). This application communicates with a piece of hardware via serial. When we got to Windows XP we started receiving reports of the app dying after a short time of running. It seems that the serial comms just 'died' and the app was left in a stuck state. The only way to recover from this situation was to restart the application.
The only information I can find regarding this problem was apparently the Windows Message system would miss that information was received, the buffer would fill and the system would get stuck. This snippet of information was left in a old word document, but there's no evidence to back this up. It also mentions that this is only prevalent at high baud rates (115200+).
The solution was to provide customers with USB->Serial converters along with the hardware.
Today: We are working on a new version of the hardware that will run across a network as well as serial ports. So to allow me to work on the network code, minus the actual hardware we are using a VSCOM NetCom113 device. It also installs a virtual comm port on the users (ie: mine) machine.
Now I have got the network code integrated with the app, it appears that the NetCom device exhibits the same behaviour as a physical commport. This is undesirable as I need the app to run longer than ~30 seconds.
Google turns up zero problems that we experience.
I was wondering:
Has anyone experienced this before? If so what did you do to fix/workaround the problem?
Does anyone have any suggestions as to whether the original author of the document is correct and what I can do to test the theory?
Unfortunately I can't post code as the serial code is tightly couple with the rest of the system, though if you have questions regarding it I can answer questions about it.
Updates:
The code is written using Win32 Comm routines - so I am using CreateFile, ReadFile. There's also judicious calls to GetOverlappedResult.
It's not hanging per se, it's just that the comms stops. You can access the menus, click the buttons, but nothing can interact with the connected hardware. Using realterm you can see that no data is coming in or going out.
I think the reference to the windows message is that the problem is internal to windows. Data has arrived but the kernal has missed it and thus not told the rest of the system about it.
Flow control is not used.
Writing a 'simple' test is difficult due the the fact that the code is tightly coupled and the underlying protocol is quite complex and would require a lot of work.
Are you using DOS-style serial code, or the Win32 CreateFile approach?
If the former, be very suspicious: if at all possible I'd convert to the latter.
If the latter, do you know on what kind of system call it's hanging? Are you in a blocking read call? or an overlapped I/O call? or waiting on an event? (I'm not sure I have enough experience to help, but those are the kinds of questions that come to mind)
You might also check into the queue size, which you can set with the SetupComm function.
I don't buy the "Windows Message system" stuff -- it sounds fishy; you can write good Win32 serial i/o code that never uses Windows messages.
edit: does your Overlapped I/O use events? I seem to remember something about auto-reset events occasionally missing their trigger... check your overlapped I/O calls very carefully to see whether you're handling the possible outcomes properly. Perhaps there's a way to make your code more robust by automatically cancelling the overlapped i/o and restarting another read. (I assume the problem is in the read half, not the write half?)
edit 2: A suggestion: assuming the win32 side has missed a byte or packet, and your devices are in deadlock because they're both expecting each other to respond to something, can you tweak the other side of the serial I/O to regularly send some type of "ping" packet with an incrementing counter? (and log the ping packets on the PC side; that way you can see whether you've missed any)
Are you sure you have your flow control set up correctly? DTR, RTS, etc...
-Adam
i have written apps that use usb / bluetooth serial ports and have never had an issue. with bluetooth i have seen bit rates (sustained) of 800,000 bps for long periods of time. most people don't properly implement the port.
My serial port
Not sure if this is a possibility for you, but if you could re-write the code using C#.NET you'd have access to the SerialPort class there. It might remedy your problem. I know a lot of legacy code based around the Win32 API for hardware I/O ports tended to fail in XP due to timing (had a small bit of experience with MIDI).
In addition, I don't know if you can use the Win32 method of Serial Port access in Vista, so that might shut out future MS OSes from being able to use your code.
I'm asked to read from and write to a half-duplex serial connection using POSIX calls (more specifically, writing in C on Linux 2.6.x). I'm having slight troubles finding detailed information on that particular model (most pages concentrate on full-duplex) and as I am getting slight anomalies when reading, I wanted to check whether maybe I am doing something wrong here.
With a half-duplex serial connection, I can only read or write. This is not a problem, as there is no unsolicited incoming data on the line - the only time any packages are sent to me (for reading) is when I asked for them beforehand.
So what my code does is to write() to the port whenever something needs to be sent. Should this data result in a response (something I know beforehand), I simply read(). There are no special functions I am calling - but maybe I should? And is this approach correct? I.e. write when the line is free?
I would read the Linux kernel source documentation, there may be a text file about the serial driver; if not, you could read through the actual driver code to see what it does (it's not as scary as it sounds, I promise!)