small footprint 3v arduino alternative to pro mini

Using Arduino Project Guidance
#1

Hello

I have been looking for a 3V arduino (or equivalent) that has a narrow footprint like the pro mini but with more pins (I am a bit short on pins to add some buttons) also the ftdi adapter is a pain to use into embedded projects

I found nothing in the arduino catalog, so I was considering using a maple mini, but it seems retired(not sure) and teensy do not seem to handle spi slave natively

any advice would be awesome (I keep digging too)

regards

#2

Have you considered the approach with 5 buttons on a single analog pin? See e.g. Arduino Playground - AnalogButtons

For the board, maybe a Sparkfun Pro Micro; has native USB and hence USB connector.

#3

The Micro has a few extra pins and on-chip USB so you get an extra hardware Serial.

The next step up is a Teensy. The 3.2 is just slightly bigger than a Mini and the Teensy 3.6 is much bigger. You get an onboard SD card slot and up to 6 hardware Serial with those.

#4

have you thought of A parallel to serial shift register? the 74HC165 is 8 bits in - but it is 5 v - should be something for 3.3 v - takes only a few pins - I have used the serial to parallel 74HC595 - 24 outputs on I think 3 pins

#5

I really like the Pololu A-Star controllers.

They have a great micro board based on the 328PB (extra UART, more timers) for only $5. But if you need more pins and native usb the 32U4 model may be fit the bill:

#6

lefstin:
I really like the Pololu A-Star controllers.

They have a great micro board based on the 328PB (extra UART, more timers) for only $5. But if you need more pins and native usb the 32U4 model may be fit the bill:

interesting, I'll check this one
thanks

#7

MorganS:
The Micro has a few extra pins and on-chip USB so you get an extra hardware Serial.

The next step up is a Teensy. The 3.2 is just slightly bigger than a Mini and the Teensy 3.6 is much bigger. You get an onboard SD card slot and up to 6 hardware Serial with those.

I have micro's but I dont want to mess with ttl conversion for 3V

#8

lefstin:
I really like the Pololu A-Star controllers.

They have a great micro board based on the 328PB (extra UART, more timers) for only $5. But if you need more pins and native usb the 32U4 model may be fit the bill:

sadly it's not 3v ttl compatible :frowning:

#9

sterretje:
Have you considered the approach with 5 buttons on a single analog pin? See e.g. Arduino Playground - AnalogButtons

For the board, maybe a Sparkfun Pro Micro; has native USB and hence USB connector.

how can I figure the frequency of analogRead() on an arduino pro mini ? would it be fast enough ? I am also updating the lcd, there is the SPI interrupt for communicating with a teensy, and also a software serial to communicate with an hc05...that seems a lot

#10

No, that's not a lot. Reading the buttons 20 times per second is enough to appear instant to a person pushing buttons. With that load you will be more like 200-1000 loops per second.

#11

Normal analogRead takes approx. 100 microseconds. If that's too slow, you can look how analogRead is implemented.

It sets up the read and starts the conversion and next waits till a flag is set indicating that the reading is finished. You can easily split that in a function (e.g. analogStart) to setup the read and start the conversion and a non-blocking function (e.g. analogFinish) to poll the flag, return e.g. -1 if not completed and read the relevant registers and return the value if completed.

#12

I'll have a look at this one...(I also thought about using an adruino micro with a voltage divider for ttl compatibility)

but how do I figure the implementation of analogRead on arduino pro micro ? I guess it changes from one to another

thanks

#13

check aliexpress and ebay for the maple mini and the blue pill

these are are based on STM32 ARM chips but you can upload via the bootloader on the maple mini clone, or upload the bootloader on the blue pill.

3.3 volt, but many of the pins are 5v tolerant
has one port with an ADC, and 2 additional pins on a second port that can be ADC

cost is low, sub- $5.00

there is a forum for the genre.. STM32.com
https://www.stm32duino.com/viewtopic.php?t=1

A good number of libraries have been ported
and a good number of the functions in the Arduino are supported.

#14

dave-in-nj:
check aliexpress and ebay for the maple mini and the blue pill

...

thanks but I checked google for maple mini spi slave, and I barely had a couple of links not even related to this

[edit : actually, it does not even work on stm32duino boards https://www.stm32duino.com/viewtopic.php?t=891]

also it seems to be discontinued

and the blue pill seems to be flooded with issues (weak usb connector, overheating regulator...)

#15

phil123456:
I'll have a look at this one...(I also thought about using an adruino micro with a voltage divider for ttl compatibility)

but how do I figure the implementation of analogRead on arduino pro micro ? I guess it changes from one to another

thanks

Never worked with a Pro Micro. You can install the board by following the instructions on the Sparkfun website; this might not be strictly necessary, I'm not sure.

#16

Would a Mega Pro Mini do?

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#17

Teensy 3.2

#18

phil123456:
I'll have a look at this one...(I also thought about using an adruino micro with a voltage divider for ttl compatibility)

but how do I figure the implementation of analogRead on arduino pro micro ? I guess it changes from one to another

thanks

An Arduino Micro is 5V. Which way is the voltage problem? You need to output or input 3V?

The digital inputs on a Teensy 3.5 are 5V-tolerant. Good for projects that only need to output 3V but there is one or two 5V inputs.

#19

How many more pins do you need than the pro mini has, and what do you need them for? It's often easier to crunch up the resources needed by your program, than it is to use new hardware.

vinceherman:
Would a Mega Pro Mini do?

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Whaaaa?

#20