Arduino like board with more than 2 UARTS

Other Hardware 3rd Party Boards
1

Hey there, I'm working on a project which requires at least one other UART beside the one USB uses. Few criterias :

1)SoftSerial is no go. I've tried that with a Uno Rev3. But since the baud rates I need for both serial port is 115200, software serial just garbles the whole data.

2)I'm currently using an ArduinoMega and code is running perfectly. Only problem is the size of the board. I'd like something ArduinoNano sized if that's not possible, maybe Uno sized.

3)It has to be compatible with arduino libraries. I'm using a Nextion LCD screen. That thing has it's own library. While I can probably port it to work on other systems, I'd prefer not to waste time. I had a maple mini clone lying around so tried to use it, but lack of documentation and libraries for that particular board(it's a chinese knock off) makes it too big of a hassle to use.

4)I'd like to use an 8 bit processor. I could easily do my project using a Raspberry Pi, but I'm actually thinking about making this project public eventually and I want to keep the cost and complexity to a minimum. Also only thing the board does is to act as a bridge between usb and lcd screen and control a few relays. I don't want to waste computational power.

5)Has to have built in FTDI. It'll be constantly connected to PC. I don't want to use an FTDI adapter.

Those are the criterion for my project. I considered Teensy 3.1 but It'd be like using a Ferrari to plough a field :confused: Any other development boards that'd be suitable?

TL;DR Version: I need a Arduino Mega with the Footprint of a Nano. Doesn't have to have too many pins 1 additional UART other than USB is enough

2

How about a 1284P board? Dual hardware serial, 16K SRAM, 128K flash, onboard FTDI module.
http://www.crossroadsfencing.com/BobuinoRev17/

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3

illusive:
Has to have built in FTDI. It'll be constantly connected to PC. I don't want to use an FTDI adapter.

i dont think there are any arduino boards with 2 ftdi. in fact hard to find boards with one ftdi these days because it is such a poor choice for usb/serial.

too bad you have size issues because mega2560 board at around 6$ free shipping is best bet for official type arduino board with 2 uarts.

illusive:
I need for both serial port is 115200, software serial just garbles the whole data.

you are using a bad library or doing something else wrong because soft serial has more accurate baud rate than hardware uart and does a great job for most projects.

4

How can a Mega2560 board, with a microcontroller that sells for $10.45 each in 1000-lot quantity, sell for $6?

Somebody is cheating on the rules of fair play in the marketplace. And free shipping too. Can't ship anything in the US for free, that's for sure.

5

CrossRoads:
How can a Mega2560 board, with a microcontroller that sells for $10.45 each in 1000-lot quantity, sell for $6?

bob, you really need to get out more. horizons extend far beyond digi-world. in the last week i have purchased 10pcs atmega2560 ic for $28.80 shipped ($2.88 ea).

and no, they are not clones, at this level of technology there is no such thing.

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6

A teensy LC seems like it would be a good fit, and hard to beat price-wise without resorting to sites that don't offer any support for anything...

7

The top listing shows 275 sold. That's hardly sufficient qty to bring material costs down to cover the price they are selling the card for.

8

i doubt if any of those sellers manufacture the boards they sell. virtually all these guys are drop shipping and even then from warehouses not oem. vast majority of their customers are in china too.

it isnt qty or scale of production so much as customer base that actually have more brains than money.

ps you can actually mail for free in usa. i accidentally posted an electric bill w/o stamp. guess what... it arrived! not the first time either. lol

9

The post office won't mail boxes for free, and definitely not internationally.

10

CrossRoads:
How about a 1284P board? Dual hardware serial, 16K SRAM, 128K flash, onboard FTDI module.
Cross Roads Electronics

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46$ + shipping
For that money I could buy 2 chinese android tablets :slight_smile: , not to mention I'm not in USA so shipping would be long and expensive

11

The Teensy LC was already proposed. You could also consider the Teensy 3.2. It is still a 3.3V ARM board but at least the digital inputs are 5V tolerant which might ease the adaption of the board. And even the Teensy 3.2 is below 20$.

12

Well, his Bobweeny (err...) is $22 - and it sounds more like what you want than his full-sized one.

It needs a serial adapter, but those are cheap (can be had for a few bucks on ebay et. al - there are CH340G-based adapters with the correct pinout available for a couple bucks now, don't buy anything with an FTDI chip on it from ebay sellers due to the possibility of getting counterfeit - google ftdigate for more info)

13

Dande80:
The Teensy LC was already proposed. You could also consider the Teensy 3.2. It is still a 3.3V ARM board but at least the digital inputs are 5V tolerant which might ease the adaption of the board. And even the Teensy 3.2 is below 20$.

I have a feeling that I'll end up using Teensy. Man, that will take weeks to ship here and I really wanted to push the limits of 8 bit with this project.

Now that I think about it, If I won't be using arduino, I could just go ahead and use the new Raspbery Zero. At least I won't have to bother with serial and could just use wireless... Not to mention it's cheaper and I can source locally.

14

Where are you from? At least in Europe Teensy Boards are available from local vendors. And they are quiet solid, the software support for them (using the Arduino environment) is very well and Paul does an amazing tech support.

15

Dande80:
Where are you from? At least in Europe Teensy Boards are available from local vendors. And they are quiet solid, the software support for them (using the Arduino environment) is very well and Paul does an amazing tech support.

Turkey. I found two distubutors for Teensy here. They are all out of stock (of any kind of Teensy board) Guess that speaks well for the board.

I'm aware of the amazing support provided for the teensy. The lcd driver library he coded in assembler made me feel pretty inferior. I even considered returning my engineering diploma ;D

16

illusive:
TL;DR Version: I need a Arduino Mega with the Footprint of a Nano. Doesn't have to have too many pins 1 additional UART other than USB is enough

What's wrong with a MEGA and one add-on serial to USB interface breakout?

And, if you don't like FTDI (can't imagine why since these work the best for me), there are other serial <-> USB boards available.

You should know that if you need exactly 115200 baud, no Arduino with a 16 mHz oscillator will do it. You get 117647 baud with a 16.000 crystal.

To get perfect 115200 (and other standard baud rates), you need an appropriate crystal such as an 18.432 or 22.1184 (or other frequency that's integer divisible by 115200).

17

Krupski:
What's wrong with a MEGA and one add-on serial to USB interface breakout?

And, if you don't like FTDI (can't imagine why since these work the best for me), there are other serial <-> USB boards available.

You should know that if you need exactly 115200 baud, no Arduino with a 16 mHz oscillator will do it. You get 117647 baud with a 16.000 crystal.

To get perfect 115200 (and other standard baud rates), you need an appropriate crystal such as an 18.432 or 22.1184 (or other frequency that's integer divisible by 115200).

I think I wasn't clear, I don't need 2 USB ports. I need one usb to connect to my computer(a c# program is sending data over serial) and one serial to connect to my lcd screen.

What's wrong with Mega is it's size, this thing will sit on my desk, I don't want anything bigger than what's absolutely necessary.

I don't need exactly 115200. It's just 57600 is the absolute minimum, and 115200 would give me room for some extra features I could come up with in the future.

What I'm trying to accomplish in my project is kindof a telemetry screen that'll connect to my PC and show various useful information. Like CPU clock speed, GPU clock, date,time, running applications etc. And I want my screen to refresh at least 24 times a second for smoother animations.

That's why I need all that bandwidth. C# program sends string like

"*/CPU1,10,10,10,20,10,20,30,50*"

Those string are around 60 to 100 bytes each. Arduino parses that string and sends them to the LCD's GPU.

This might not look like much, but there are other packets being sent. Temperature, net statistics, volume info etc. And I'm trying to send each packed 24 times a second... There are probably better and more efficient ways to do what I'm doing, but this is the best I came up with. As you might guess, it requires truckload of bandwidth.

18

There are smaller versions of the Mega on ebay, $20-25 each.

There's the Teensy (but it's not an 8-bit AVR, so if you're planning to use a library that isn't available for teensy, that'd be a problem).

There's the Bobweeny 1284p board, and his mini breakout board.

Or you could use a piece of general purpose prototyping board to build your own with a 1284p in DIP package.

Or you could use some other non-Arduino compatible microcontroller with multiple UARTs.

Or you could use one of the newer style arduinos, like the Zero, Due, or 101.

24 samples per second is significantly higher than you really need, I think. If the reason for sending so damned much data is just to make smoother animations, there's nothing that prevents you from having the arduino do the smoothing...

19

I have a feeling that I'll end up using Teensy.
Now that I think about it, If I won't be using arduino,

A teensy is still Arduino, for all practical purposes. It probably has more effort put into making it compatible with the arduino libraries/etc than most of the "compatibles" (including some of the 32bit Actual Arduino products. Sigh.)

I could just go ahead and use the new Raspbery Zero.

You can get Raspberry Pi Zero more easily than you can get a Teensy??!! Wow! Around here, Pi Zeros sold out on about "day 2" and haven't been available since (nor have I seen any indication of when they WILL be available.)

You could also consider some of the newer ATtiny chips. ATtiny841 and Attiny1634 have two uarts, and mini-sized breakout boards available from DrAzzy: http://drazzy.com/e/tiny841.shtml (no built-in USB/Serial, though.)

20

I'm enjoying my 20mhz 1284p. 2 UARTS. Functional. Price is a little more for the DIP40 chip but they go for around $5 - $10. Not talking board mind you. Just the MCU.