Data Transfer Rate in Ardunio

by Matthew Ford 10^th Dec 2016 (originally posted 10^th Aug 2014)
© Forward Computing and Control Pty. Ltd. NSW Australia
All rights reserved.

How fast can Arduino transfer Sample Data
this page has been superseded by
Remote High Speed Data Logging using Arduino/GL AR150/Android/pfodApp

Introduction

pfodApp can plot incoming CSV (comma delimited values) data in real time, so a common question is
“How fast can I plot data?”
The simple answer is:- (see Remote High Speed Data Logging for a more detailed answer)
“If you have a recent multi-core mobile, then Arduino Uno is the limiting factor. At 115200 baud you can send about 500 data pairs per sec maximum. That is about 1mS per 9 byte field.”

The maximum speed you send sample data depends on:-

1. the baud rate for transferring the bytes off the Arduino card

2. the time required to convert the numeric data into bytes (e.g. Serial.print(data) )

3. the time used by the rest of the Arduino loop() to collect and scale the data, and do what ever else the loop() is doing.

Guidelines for Maximum Sample Data Rates

In order of importance.

1. Use 115200 baud rate hardware serial connections. (SPI connection to the Ethernet shield is slower when tested on Uno)

2. Use faster Arduino processors. (The timings below use an 8Mhz Arduino. The Mega uses 16Mhz)

3. Avoid floating point operations particularly division as they are much slower then integer operations on most Arduino boards

4. Send integer data instead of floating point. The Print statements format faster.

5. Keep the rest of the loop() quick. Avoid delay() and use polling or interrupt operations in preference to the operations that wait for results. See Polling Analog Reads for example.
   
   
   

A Test Sketch

Here is a simple sketch to test the data transfer rate. It prints out the time in milliseconds every 1000 loops and sends on line of CSV per loop to the pfodApp.

Sending 16 bytes as two 7byte fields takes less then 2ms per sample on 8Mhz FioV3 using 115200 baud connection to a Roving Networks Wifly wifi board. Most of the time is consumed transferring the bytes at 115200 baud, since the loop() is not doing much else and the sketch is sending integers. This is about as fast a you can go.

For use of the Arduino name see http://arduino.cc/en/Main/FAQ

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