I'm eventually trying to use transparent data transmission to pass messages between the mobile SDK and an onboard device using the A3 API/UART port.
Right now I used DJI assistant to output a timestamp to the API port at 1hz. When I connect a TTL>USB device, I see garbage data coming through. When I connect an oscilloscope with a protocol analyzer, I see one frame every second, but the frame is variable size. The ASCII representation of what does come through is nonsense.
I have double checked that baud is set correctly (and have tried other baud rates). I've made sure the grounding is proper. I've tried probing the pin on the actual A3 port (to remove possibility of EMI on the serial cable). It seems like I'm getting garbage data on the serial line, or I don't know how to decode it properly.
Hi，maybe you can refer to the open-protocol of M100 Link.I think it's difficult to decode the protocol of N3,unless DJI publishes that。
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What I've been trying to do is send UART communications from an STM32 L152RE Nucleo board to an ESP32, however when I attempt to send these communications I get nothing on the ESP serial monitor. What I am able to see is the STM32 sending messages to its own serial monitor which is great but not what I want.
What I've read so far is that UART 2 is connected to ST-Link so that it can do specifically what I've been witnessing and it explains how this can be reconfigured to allow for the messages to be sent to a peripheral UART device but I'm not sure exactly how to do that.
So in the picture below it says to do this I need to "turn off" SB13 and SB14 and "turn on" SB62 and SB63. I don't really understand how to interpret that, other than to mean "remove resistors from SB13 and SB14 and Place them on SB62 and SB63", is this correct?
I know there are another set of UART pins on the board, can I use those instead somehow?
Your guess ist correct. "SB" means "Solder Bridge". It is just a pair of pads which can be connected with a solder ball, like a simple jumper. Setting SB13 to ON means to connect the pads with a solder ball, setting SB62 to OFF means to remove an existing solder ball connection.
Using a different USART is even easier. Have a look at the STM32L151xE Datasheet to find out that e.g. USART1 is available on pins PA9 (TX) and PA10 (RX). According to user manual of the NUCLEO-L152RE board these pins are available on the ST morpho connector CN10: PA9 at Pin 21 and PA10 at Pin 33.
We are using two USRPs and GNU Radio Companion to build an OFDM radar. The first USRP is the N210 which is used as a transmitter through its Tx/Rx port. The second USRP is N200 which is used as a receiver through its Rx2 port. They are connected together through the so-called MIMO cable to synchronize them. The N210 is connected to the host PC through the gigabit Ethernet cable. The samples that feed the transmitter USRP comes from a block "File Source", and the samples that are collected from the receiver USRP goes to a block "File Sink".
Initially, an external loopback cable is used between the Tx/Rx port of N210 and the the Rx2 port of the N200. Whenever we run the flowgraph, we expect that for every sample that is transferred from the File Source to N210, there should a corresponding sample with somehow same value that comes from N200 to File Sink. However, we have noticed that the N200 produces a stream of random samples before the awaited samples start to appear!!! The length and the values of this stream of random samples varies each time we re-run the flowgraph!!! Of course this issue constitutes an obstacle for our application because in radar the range of the target to be detected is estimated depending on the delay time. The latter is computed from the number of noise samples at the receiver that precedes the reception of the actual transmitted samples.
The question is: How can we guarantee or force the receiving USRP (N200) not to receive any sample before the transmitter USRP (N210) starts to transmit the required samples? Should not this be the task of GnuRadio?!!!! or we have to do something in GnuRadio to force this to happen?
thnx
We are using two USRPs and GNU Radio Companion to build an OFDM radar. The first USRP is the N210 which is used as a transmitter through its Tx/Rx port. The second USRP is N200 which is used as a receiver through its Rx2 port.
This sounds like you're reproducing my 2013 bachelor thesis!
Whenever we run the flowgraph, we expect that for every sample that is transferred from the File Source to N210, there should a corresponding sample with somehow same value that comes from N200 to File Sink.
No, that would only work when you start and stop both USRPs using the same command times and the same number of samples to be acquired.
However, we have noticed that the N200 produces a stream of random samples before the awaited samples start to appear!!!
Well, over-the air delay, and the state in the DSP chain. This is expected. Use timed commands to make the timing deterministic, and you'll know how many samples to ignore.
I'm trying to implement S-MAC protocol on waspmote xbee sensors and i know it has its own CSMA/CA. So first of all I need to understand the basic of xBee collision avoidance.
Two senders set up in api mode in libraries and both periodically sending single bytes to a common receiver. I reduce the delay and many changing in libabries to make collision and to see how algorithm works. But when i monitor data at the receiver all looks as expected at the receiver .. byte1, byte 2 .. byte1, byte2.
Do u have any idea how can i make collision?
Are you sniffing the 802.15.4 traffic? That's the only way you'd see a collision.
The XBee module buffers the data you want to send, using the host communication parameters (baud rate, API mode, etc.) and then sends it out over 802.15.4 at 250kbps. The module has all of the collision avoidance built in, and will retransmit as necessary to deliver your message. If it's unable to deliver after some number of transmission attempts, you'll get a Transmit Status frame indicating failure.
On the receiving end, it buffers the data and delivers it to the local host using local serial settings (baud rate and API mode).
If you're trying to implement S-MAC, you need a different radio processor where you have low-level control over the radio. The XBee module provides an application layer and handles the MAC layer itself.
I am using Arduino Leonardo to transmit an string to a wifi module. The format of command that wifi module can recognize is:
AT60,1,content to a server
I am using an virtual server(TCP/IP Builder) to test the content I can received.
Here is the content I want to send:
smart/device/deviceCmd?userId=1010002003&deviceId=A00019999990002&cmd=ON
Since I try to send it again and again, I use a loop to send it. In the virtual server side, the content I got is:
smart/device/deviceCmd?userId=1010002003&devceId=A00019999990002&cmd=ON
smart/device/deviceCmd?userId=1010002003&devceId=A00019999990002&cmd=ON
smart/device/deviceCmd?userId=1010002003&dviceId=A00019999990002&cmd=ON
smart/device/deviceCmd?userId=1010002003&eviceId=A00019999990002&cmd=ON
smart/device/deviceCmd?userId=1010002003&devieId=A00019999990002&cmd=ON
smart/device/deviceCmd?userId=1010002003deviceId=A00019999990002&cmd=ON
smart/device/deviceCmd?userId=1010002003&dviceId=A00019999990002&cmd=ON
smart/device/deviceCmd?userId=1010002003&dviceId=A00019999990002&cmd=ON
smart/device/deviceCmd?userId=1010002003&deiceId=A00019999990002&cmd=ON
smart/device/deviceCmd?userId=1010002003&dviceId=A00019999990002&cmd=ON
This is the QUESTION: There exist one terrible mistake in the content I received, which is the deviceId part never correct. It's so weird.
Here is part of related code:
//In Uart.cpp
//These three lines can sent a formatted string as "AT60,1,content"
Serial1.write("AT60,");
Serial1.write(channelID); //channel ID = 1 here
Serial1.write(reportIsFire, 76);
//In Uart.h
//Definition of the string I need to send, which has 76 characters.
char reportIsFire[76] = ",smart/device/deviceCmd?userId=1010002003&deviceId=A00019999990002&cmd=ON \n";
Here is few background of this application:
I am using Arduino 1.5.8 IDE with VisualStudio
Since the serial buffer of Arduino is only 64 Bytes, I have already
change the buffer size to 128 Bytes in "HardwareSerial.h" to send
out this large string.
The baud rate is 115200 and I am using Serial 1. I have used Serial 1
to transmit few other characters and it works fine.
I will appreciate that If you have any idea about this question.
I am betting that the serial baud rate of the Arduino is not 100% correct. Increasing the buffer size will not matter if the data is being lost due to a timing issue in the physical link.
I'd recommend double-checking the code that initializes the serial baud rate generator. It may be possible to get a closer rate to 115,200 by either adjusting the available settings, altering the main clock speed (if possible), implementing some form of flow control, or all of the above.
In extreme cases, you may consider using a special-frequency oscillator. Many Microchip PICs use an internal or external 4MHz or 8MHz crystal, but this can produce far too much timing error for lengthy serial transmissions at high speed. In that case, something special, like a 7.3728MHz crystal can be used, bringing the accuracy to exactly 100% (at least on some PIC devices.)
Lastly, another consideration is if any pre-emptive code is running on the device, such as interrupts or timers which could inadvertently interfere with the serial output.
I don't have an answer, but I suspect the most likely problem is that the Wifi card can't read characters at a sustained 115200 baud rate. If possible, set the Wifi baud rate and the Arduino Serial.begin() to a lower rate, such as 57600 or 19200.
If the Arduino baud rate was simply inaccurate, I'd expect to see the problem appearing at random locations in the string, rather than about 40 characters in.
I'm currently working on a project which involves dealing with a HW device tailor-made for this purpose.
The device will serve the purpose of sending certain data via serial port (COM1, for instance). The data it is supposed to send doesn't matter that much.
I already have some knowledge regarding Windows serial port communication. CreateFile, WriteFile, and so on... BUT...
There is one "engine" on the device, which will send me the data when I ask it to, and in order to do so, I need to send there a signal (10101010) the rate of which will indicate the clock rate of that device "engine".
Here comes the explanation of how this device work. It gets a signal to send data through one pin. I'm supposed to send there 0 for start, 1 for end. Then, after this, it will watch some other pin for signal, sample it, and based on the frequency of ones and zeroes I send to it, it will start sending data via the thrid pin.
My questions are:
How to access individual pins of COM port?
How to manage the frequency and any delays I will need by myself?
I think that maybe I will have to do on this in kernel more by use of device drivers which will have to be developed.
There is an easier way. The COM port will send out the signal of alternating 1s and 0s if you just send a 0xAA byte.