Arduino Serial Read
- Arduino Serial Read Integers
- Arduino Serial Readstring
- Tx And Rx In Arduino Serial Read
- Arduino Serial Read Example
I'm trying to do some fairly simple serial communication and have things partially working, but am pretty confused about a couple results I'm getting.
For a little background, I'm using an Arduino Mega 2560 to try to communicate with a Dynamixel servo (MX-64) over TTL (half-duplex, asynchronous) with Tx1 and Rx1. Basically I construct some byte arrays as instructions, send them over to the servo (with Serial1.write()), and then read back a reply. I've actually gotten it to work pretty well if I use Serial1.readBytes(), specifying the length of the buffer (number of bytes I'm expecting). I'm also reading back what I originally sent (first) as well as the response (second), since I have Tx1 and Rx1 tied together (required in my setup because this servo only has one data wire).
I'm trying to do some fairly simple serial communication and have things partially working, but am pretty confused about a couple results I'm getting. For a little background, I'm using an Arduino. Arduino Function Serial.read and Serial.readString: Serial monitor of Arduino is a very useful feature.Serial monitor is used to see receive data, send data,print data and so on.Serial monitor is connected to the Arduino through serial communication. This serial communication occurs using RX. May 05, 2016 Serial data is slow by Arduino standards When anything sends serial data to the Arduino it arrives into the Arduino input buffer at a speed set by the baud rate. At 9600 baud about 960 characters arrive per second which means there is a gap of just over 1 millisecond between characters.
However I don't understand the difference between Serial.readBytes() and Serial.read(). If I do Serial.read() just prior to Serial.readBytes(), it comes back with -1, meaning no bytes to read.. but then Serial.readBytes() gives me the byte stream I was expecting from the buffer! What's going on here?
Similarly, Serial.available() seems sort of broken in that it tells me there are no bytes to read (returns 0), but then I can read the bytes I'm expecting with Serial.readBytes(). Additionally, I can do Serial.readBytes() after there's nothing left (or rather, there shouldn't be any bytes left..) and it will give me some bytes, but they're total garbage.
I think maybe there's something I don't understand about the way the serial buffer works, but can't find a good resource on it and the Arduino reference pages are kind of useless. Any clues about the difference in how these operate would be much appreciated!
1 Answer
readBytes is blocking until the determined length has been read, or it times out (see Serial.setTimeout()). Where read grabs what has come, if it has come in. Hence available is used to query if it has.
Note that it takes time for a message to go out and to receive either the echo or response. So simply checking the RX buffer immediately after sending something, is expected to be empty for some time. That is where readBytes sites and waits. And I bet the default setTimeout of 1s is sufficient, to get the response.
This is why you see the Serial.read() inside a while or if Serial.available. Hence I typically employ something like the following: Which emulates readBytes (for the most part).
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Above code was quickly written and untested. But gets the idea across.
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I have this code below where I got from this forum that I followed through. It did not work for me but they claim that the code is fine. I already tried several string comparison methods such as string.equals(string) and the standard operator, still with no luck.
5 Answers
I am able to solve last night problem by simply adding readString.trim(); before string comparison. This is because there will be newline character where id did not print anything in the arduino console.
I place the function as in my code below:
Yakob UbaidiYakob Ubaidi
andrewsiArduino Serial Read Integers
I see you try to create some like command line interpreter for test;
You can use Serial command line interpreter for Arduino or just see code, how it's work.
This is not answer, but some help =)
452452Arduino Serial Readstring
solved your code is right you just have to set arduino terminal on 'no line ending' you also forgot to write this Serial.println('switching off');
Tx And Rx In Arduino Serial Read
and thanks for sharing your code i am also using your code thanks!!