32bit Controllers Needed!

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Priest
 
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32bit Controllers Needed!

Post by Priest »

Hello all,

Our design team at Colorado State University has recently run into a critical design flaw that could use your help! We are currently tasked with building a low-cost mechatronic device for use in High Schools. To that end, we have initially chosen Arduino. Unfortunately, we have come to find out that the 8bit 16MHz chips simply aren't powerful enough for our needs (more on that later).

We chose Arduino for the following reasons:
1: Large Ecosystem (Hundreds of Forums)
2: Open Source
3: Well Documented
4: Affordable (<$60)
5: Simplified Codebase (Simplified C)
6: Market Stability (Foreseeable to still around 10+ years from now)

Our system, however, requires the integration of one or more stepper motors, along with concurrent gathering of Accelerometer data, and save-data processes to SD Card. We found out only yesterday that running one Stepper Motor at 3200 Steps/Revolution on the Arduino Uno R3 completely maxed out all of it's processing power. As such, we are seeking a more powerful uC, but we need to still fulfill the 6 objectives above.

To that end, we have heard a few recommendations. The first we heard of is chipKIT. We are also looking at the Arduino Due. What I can't seem to find a firm answer on is the following:

1a. Can the Arduino Due still be programmed in Simplified C?
1b. Would existing Libraries that come with the Arduino IDE work on the Due?

2a. What other 32bit, 80MHz+ boards exist out there?
2b. Can any of them be coded using the Arduino IDE?
2c. Do any of them use the same Codebase?

Our main problem is that we don't want to leave the Arduino Ecosystem, and we don't want to change to an overly complicated or obscure code-base that High School students will not be able to find good online support for. Similarly, we need these boards to be roughly the same cost as the Uno or the Due, depending on how many Pin-outs there are.

We are desperately seeking help and advice to move forward with our project.

Thank you in advance,

CSU Mechanical Engineering Senior Design Team

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adafruit_support_bill
 
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Re: 32bit Controllers Needed!

Post by adafruit_support_bill »

We found out only yesterday that running one Stepper Motor at 3200 Steps/Revolution on the Arduino Uno R3 completely maxed out all of it's processing power.
Before you give up on the Arduino - Which stepper controller were you using? If you were using the Adafruit Motor Shield V2, the limiting factor is the I2C bus speed. This can be increased by a factor of 4. http://forums.adafruit.com/viewtopic.ph ... 32#p214932

There are other stepper controllers that do not use i2c and would consume less processing time. If you do not need to run very many motors, these would be an option. www.pololu.com is one source.

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michaelmeissner
 
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Re: 32bit Controllers Needed!

Post by michaelmeissner »

I like the Teensy 3.0. It is a MK20DX128 32 bit ARM, Cortex-M4, 48 MHz (over-clock to 96 Mhz, underclock to 24 Mhz), 128k flash memory, 16k SRAM, 2K EEPROM, 34 pins, 3.3v, 12 analog pins, 10 pwm pins, 3 hardware UARTs, 1 i2c bus, 1 spi bus, i2s (I'm not sure of the level of support for i2s). It has a real-time clock if you add a crystal, with holes to attach a coin cell battery to keep the clock powered if the main Teensy is off. It has 4 general purpose DMA channels (separate from USB). Some of the pins can also act as touch sensors. It is programmed via a micro USB-B cable (not provided, but same cable used by many phones/tablets). It comes in a DIP-28 size, for easy breadboarding (with 24 pins available when in a breadboard, and the other 10 pins are available if you are willing to solder pads underneath the Teensy 3.0). It costs $19 with the header pins unsoldered, and $22 with the pins soldered. http://www.pjrc.com/teensy/index.html

Adafruit also resells the Teensy 3.0: http://www.adafruit.com/products/1044.

You first install the 1.0.x Arduino IDE, and then run the PJRC installer, which overlays the Teensy 3.0 support. It uses the Arduino IDE as a basis of the normal programming.

Here is the place that describes what libraries have been tested (and fixed) to work with the Teensy 3.0: http://www.pjrc.com/teensy/td_libs.html.

Finally, here is the Teensy forum: http://forum.pjrc.com/forum.php

Priest
 
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Joined: Mon Oct 21, 2013 10:35 am

Re: 32bit Controllers Needed!

Post by Priest »

Which stepper controller were you using?

We are using the Big Easy Driver. When we started using this, we found we couldn't even drive the Stepper at 1 Hz. We posted on the AccelStepper Library forum for assistance, at which point Brian Schmalz himself (Designer of the Big Easy Driver) informed us that the Uno would not be able to handle 1/16th microstepping at above 1 Hz.

Our system requires concurrent use of 1-3 Stepper Motors of high Accuracy (1/8th step or higher, up to 200 RPM), 2-3 Accelerometers, and SD Card Read/Write cycles (Logging Accelerometer Data). As such, we need significantly more processing power beyond just the one stepper motor.
I like the Teensy 3.0
Thank you for your input, Michael - we will look into Teensy systems as another possibility!

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