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14

The Arduino Nano cannot do 800 kb/s. As you can see in the source code, the bit duration is rounded to the nearest multiple of 8 CPU cycles. In your case, it is rounded to 3 × 8 CPU cycles, which yields a baud rate of 666.666 kb/s. That is 16% too slow, an error too large for any communication to be possible. At 400 kb/s ...


11

OK. So, I tried the SDFat lib. This library is definitely better than the default SD library that comes with adruino. But that is not how I solved my problem of low data-rate. I followed the instruction of the author of SDFat library from this post. According to fat16lib, to increase the data rate we need to use flush() wisely. We would want to write() the ...


10

The problem is most likely that the system is going to sleep while it's still sending the serial data. Forcing all the serial data to be sent before you go to sleep should fix the problem (serial data is sent in the background using an interrupt so as to keep sketch slowdown to a minimum): Serial.flush(); LowPower.powerDown(SLEEP_1S, ADC_OFF, BOD_OFF);


7

Depending on how recent a version of the AT Instruction Set interpreter your chip has, the two instructions you tried may not be valid ones; they are not listed in Espressif's ESP8266 AT Instruction Set document. Searches for either "CIOBAUD" or "IPR" in the current document (version 1.5.3) return no results. The baud rate commands are now "AT+UART_CUR" ...


7

You are saving a String object in EEPROM, which is useless. A string object does not store the contents of your string. Instead, it just stores: the memory address where the actual contents (the characters) is stored the amount of memory allocated for this contents the number of characters that actually make the string This is what you are storing to, and ...


5

I am not aware of anything like that, no. The problem is what you are seeing as characters are a complete corruption of the data. Only some part of it may have been interpreted as a valid bit sequence, and even then you can't know what bit it was. However, there is one magic character in UART communication: U What is special about that character is its ...


4

When in double-speed mode, as noted in the manual, fewer samples are used. In Asynchronous serial communication, there is no clock signal, so the clock that keeps the two devices in sync is extrapolated from the data signal. Each end of the communication has it's own clock source (crystal oscillator, ceramic resonator, R-C oscillator, etc.), and you'll ...


4

Have you tried setting the web editor's baud rate to both the old and the new values? I ask because the CIOBAUD command has been obsolete for a while now so, depending on the age of your device, it may have done nothing. The command was replaced by "AT+UART_CUR" and "AT+UART_DEF" which have a different syntax. See this answer to a similar question. Update: ...


4

Avoid the handshake getting a buffer! Use SD.write(buf,size); Hi every one, I'm working in a project with the same issue. I was following the same steps of yours and got exactly the same numbers. I've just fixed it out. The problem is the handshake when you call the SD.write(). Instead: //for each loop, it is going to make a handshake while(<...


4

I had these images lying around so here is an example of "Fab" being sent at 9600 baud: And now a single byte (the letter "F"): A - no data (Tx is high) B - The "start bit". The line is taken low to tell the receiver that a character (byte) is commencing to be sent. The receiver waits for one and a half clock times before sampling the line. C - First ...


4

Many factors would decide if you can reach this wanted speed. Only some of these. 1. Your Software The SdFat Library is faster than the standard SD Library of the Arduino IDE. It also has an easy to use compatibility function with the standard SD Library. Try it out. 2. Your Hardware You should use a high class SD Card. As you maybe know SD Cards are ...


3

I bricked my Esp with the same command, too. After hours of searching I found a way to reset the bricked esp. https://developer.mbed.org/users/sschocke/code/WiFiLamp/wiki/Updating-ESP8266-Firmware I had to set the baudrate to 115200 instead of 9600, and between the uploading files I had to disconnect the esp from power. I hope that helps you and everybody ...


3

I Connected an FTDI232 module at 115200 baud and could read the specs of the ESP8266 module now: AT+GMR AT version:0.40.0.0(Aug 8 2015 14:45:58) SDK version:1.3.0 Ai-Thinker Technology Co.,Ltd. Build:1.3.0.2 Sep 11 2015 11:48:04 OK After that I sent the AT+IPR=9600 command, which first seemed to do the trick. But after reboot of the module, all I got ...


3

Setting baud rates in a C program isn't a trivial task. You need to use the low-level open() instead of fopen() and act on the returned file descriptor with ioctl() or tcsetattr() / tcgetattr(). The former method allows the setting of non-standard baud rates while the latter only allows specific baud rates to be used. I wrote a C++ class to deal with it ...


3

As explained in jose can u c’s answer, in double speed mode the UART has fewer samples for doing clock and data recovery. But this doesn't help answering the second question: Why does it seem to be set in the code by default? Double speed mode has also an advantage: it enables higher resolution in setting the baud rate. In normal mode, the bit duration ...


3

Just to have the full working code, I ended up with this: #include <EEPROM.h> char serial_characters[] = {"ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"}; // 7 chars for serial and one for string end '\0' char serial_number[8]; void setup() { Serial.begin(115200); EEPROM.get(0, serial_number); // check found format if (serial_number[0] == 'S' &...


2

Try measuring pulse width and match shortest pulse against pre-defined widths corresponding to available baudrates. This way you can detect baudrate by analysing random binary stream. Signal glitches, such as very short spikes, will be filtered out, as they will never match the list of baudrates. Repeat the measurement few times to raise accuracy and ...


2

If I change it back to 115200 baud, it uploads fine...even though the sketch itself initializes the serial port to 57600. The bootloader is a piece of code designed to work at a specific baud rate. As KIIV said in his answer only the USB-based Arduinos would be relatively immune to changing the rate. What your own code does, after being uploaded, is ...


2

First, look at the code used by the Arduino core library to configure the USART baud rate register: it's in HardwareSerial::begin(). The general formula is uint16_t baud_setting = (F_CPU / 4 / baud - 1) / 2; but beware of the hard-coded exception. You can replicate that part of the code in your own. Then, look at the ATmega328P datasheet. More ...


2

The baud rate you specify in your program and the baud rate in the serial monitor must match. The ESP8266 outputs a boot message at its own baud rate (varies from model to model - try 57600) before it executes your sketch. For example: You can choose any (within reason) baud rate in your program as long as you also choose the same baud rate in whatever is ...


1

Using the ESP8266 in general The easiest, most flexible, and most efficient way is to program the ESP8266 directly. If it is possible, have it replace the Arduino entirely. To do this, it is best to get an ESP8266 development board that breaks out all IO pins and has a USB interface for easy programming. Programming these development boards is just like ...


1

AT+UART_DEF=9600,8,1,0,3 Are you aware that this configuration (3) as a rule would require both RTS and CTS extra physical signals to work ? That means, if you do not connect anything there, the level present at some pin configured anywhere would prevent ESP8266 from receiving further data from serial. In general people use "no flow control" (0) AT+...


1

How is that possible that it has two different baudrates? Very simple. Exactly the same as the Arduino. If you put: Serial.begin(9600); in your program then your sketch runs with the serial port at 9600 baud. However, just before then, the bootloader runs at 115200 baud for a few seconds listening for instructions from the PC. There's no magic there. ...


1

I've found 9600 baud to be the receive limit among standard baud rates (transmission can go faster). You're proposing an 8% increase over 9600 which sounds like it has a good chance of working but you'll need to experiment to find out. You also asked why might your data (on the LCD) be wrong. You'll do your sanity a big favor and do two separate ...


1

I have no enough reputations to make a comment so I will drop my two cents here. Are you changing the baudrate at both sides? I have been using the arduino's built-in UART library for a while using different baudrates with no problems. Your problem could be an issue related to the library you are using.


1

Arduino bootloaders doesn't have any baud rate detection and baud rate is fixed (for the different boards there might be different baud rates) Only Leonardo (and others with native USB) are almost idependent on baud rate except for 1200bauds used as "reset". (However it runs at maximum speed that the MCU can handle)


1

To answer your specific question, yes you can alter the baud rate after an event. Just use a Serial.end() then a Serial.begin() with the new baud rate.


1

Is it possible to overclock the baudrate from the mega to 230400 bps? Yes, setting that baud-rate is not a problem but this specific baud-rate may will give a high error rate. According to the AVR baud-rate calculation (UBRRn Settings for 16 Mhz system clock) the error is 8.5% (U2Xn=0) and -3.5% (U2Xn=1). Simply choosing 250000 bps will remove this error. ...


1

Using this firmware: https://developer.mbed.org/users/sschocke/code/WiFiLamp/wiki/Updating-ESP8266-Firmware and this flasher: http://yaab-arduino.blogspot.com.br/2015/12/flashing-esp8266-firmware-arduino.html i was able to recover my esp 8266 12f


1

One sensor has a baud rate of 115200, the other 9600. I think this will create problems in the serial because I can only choose one baud rate. Why do you think the sensor has a baudrate? Both the sensors seem to use the "serial connection" of the Arduino to log their information. What do you think? The first sensor is the pulse sensor, ...


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