What is the maximum data transfer speed using SPI interface on Arduino?
I have an Arduino Nano and I want to transfer data between it and a Raspberry Pico. I use SPI interface, and I want to know, what is the data speed limit (in bit per second).
If you take a look into the Atmega328p datasheet, then there is:
F_OSC/2 in Master mode (with double speed SPI bit set), otherwise F_OSC/4
As a slave at best F_OSC/4
Related
I have a project in hand where I need to connect 5 or more arduinos as slaves to Raspberry Pi. Load Cells, Reed Switch, Solenoid lock will be connected to each of the arduino. The arduinos need to send the weight readings when a communication is started by the raspberry pi(master). Only a single arduino will be activated at a time. The arduinos will be placed at a maximum of 6ft distance from the raspberry pi. I need advice regarding how to make this connection. I read that I2C cannot be used for long distances so I am unsure if 6 ft is a long distance for I2C. Next, I am trying to see if a USB would work for my case but the issue is the Pi has only 4 USB slots. So can I use a external USB hub with an external power supply and connected each of the arduinos to the USB hub and provide individual power supply to the arduinos? Will this arrangement work or should I be looking at any other protocol apart from I2C and USB?? Any advice on this will be much appreciated. Thanks a lot for your time.
Arduino (Nano, Uno, Mega etc.) can communicate via SPI, I2C or UART.
Long story short, SPI is not suitable for your application. It is used for fast data transfer over short distances (usually milimeters or centimeters), so mainly for communication between chips mounted on the same PCB or PCBs close together (e.g. display shields).
Using I2C is perfectly fine (let's say up to 10 meters) and in your case it is a way to go. The maximum possible length depends on baud rate, for 10 meters a 9600 baud rate would be OK. The big advantage is that you need only 2 wires to connect all Arduinos, the disadvantage is that only one device can transfer data at the time – in your case, that does not matter.
UART is used for communication with many external modules (GSM, GPS, HMI, ...) and also in combination with USB-TTL chip for communication via USB (virtual COM port). In your case, you can use UART e.g. in combination with external UART-RS485 converter module, but there is no need since you can use I2C.
I am working with Arduino yun, and I would like to know how can I access sensor values from one arduino using another arduino. Which ways of comunication they are between arduinos? Can I access data from another arduino through wireless? Do I need additional hardware to accomplish this, or its possible with just two arduinos and one computer?
It is possible. Arduinos, depending on the model, can usually communicate via SPI, I2C, etc. Both Arduinos can send and receive data via SPI, for example, so you can hook them up to each other.
It also depends on the type of sensor data you have as well as how many open pins you have: if you really wanted to, you could set 8 bits of data to 8 different pins, and simply connect those pins to 8 pins on the receiving Arduino. That's a rather barbaric way to do it considering you have SPI at your disposal, though.
There are a couple of ways, without any external hardware you have :
SPI
I2C
Serial communication/UART
Serial is the easiest to use among these 3.
And for any other kind of communication you will require external hardware, so if you want to go wireless, then you have cheap RF modules, XBee, etc..
That said that's more appropriate question for Arduino SE site ;)
Check this page. https://www.arduino.cc/en/Tutorial/MasterWriter
I used the I2C to trigger sound from on one arduino and play it on the other. There was no noticeable delay. If you want to stream a lot of data then SPI should be used.
I'm on a project in which I must read the DC (1ms-2ms) of 16 PWM signals with 4 Arduino MEGA 2560, 4 PWM for each one. After have read it, I should send the 16 values to a computer. The initial idea was to use 4 Arduino Ethernet Shield connected to a router and then get on the computer. The other option is to connect the 4 Arduino directly by USB to the computer and perform it with each Serial.print. Which of the two options could give me better results? I have to emphasize that time is important, less than 20ms to receive the 16 PWM values would be optimal.
A greeting and thanks.
20ms is not really an issue here. Assuming you connect the Arduino over USB, using Serial, at 115,000bps, you can send the 4 bytes (Assuming a byte per Duty Cycle reading) to the control computer in .35ms.
Using TCP/IP, and a direct Ethernet connection, it will be orders of magnitude faster than that.
So, I would say, what are you more comfortable with in coding terms? The serial approach will be easy on the Arduino, but you might have to work a bit harder on the control computer. (For instance, will you use C++, and a Serial library like Boost::ASIO ?
Or, are you comfortable with TCP/IP socket programming? And if so, you will have a more robust solution, which will scale better for you.
I need to connect a BLE112 to a microcontroller (msp430 family) as an spi slave device.
I've configured it using hardware.xml file, setting mode="spi_slave".
Now, how can I read data?
"hardware_spi_transfer" does not fit my need, because it also sends bytes, while I only want to receive. And also, it seems it provides clock generation, which I want to avoid. Infact, I want the device working as slave.
Thanks in advance.
I believe 'hardware_spi_transfer' is to be used when the BLE112 is the master and you want to transfer data from/to a slave that is connected to it. The configuration guide ('usart' section) seems to say that SPI slave functionality is very limited.
You probably need to connect the BLE112 USART pins to the SPI port of the MSP430. Then on the BLE112 you run a BGScript that polls for the SS pin being pulled low by the master. When SS is low write your data to the USART.
Why not just use the USART to transfer the data?
I want to use an Arduino to gather data from two sensors. This seems easy when the required baud rate for two sensors is the same. However, I'm stumped as how to go about doing this when two different rates are required.
For example, suppose I want to use a barometer and a GPS sensor at the same time. I imagine I'd have to modify something lower-level for one of the sensors (possibly in the libraries or supporting functions), but where do I begin?
Having a look at the provided material, I can see that your hardware use serial communications. The barometer uses an I²C port and the GPS a serial port.
The "communication speed" (or baud rate) does not have to be exactly the same for all devices. Indeed, your sensors may have different sample rate or different needs, and thus does not need to communicate with the central unit with the same frequency.
I would suggest to go step by step. Try first with the GPS sensor. I think serial ports are easier to start with. Try first (a) to communicate directly with the GPS through your computer (you can use your Arduino to set up a USB-serial connection), and later (b) try to write some code which communicates in the same way with the GPS but now from Arduino.
Simple method for Doing this. You have two Serial Port
SoftwareSerial
hardwareserial
In software Serial is one You communicate Directly . in hardware serial you configured for particular pin as Tx and Rx pin. SO barometer you can use SoftwareSerial and for GPS you can use Hardware Serial.
[1]: http://arduino.cc/en/Reference/SoftwareSerial
[2]: http://forum.arduino.cc/index.php?topic=49645.0