Motor Shield V1 & GPS Shield

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project_science
 
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Motor Shield V1 & GPS Shield

Post by project_science »

I have both the Adafruit motor shield v1 and the Adafruit ultimate GPS shield. I using a Leonard, and the DF Robot with 4 DC motors.

I've noticed that the RC I've built using just the Leonard + Motor Shield stacked with an Arduino wireless shield, it all works fine with plenty of power.

However, when I placed the GPS shield into the stack, I've noticed that the power isn't as good, and the wheels stutter some. Basically, it's not fluid like it previously was.

Is the ultimate GPS shield and the Motor Shield interfering with each other somehow / or competing for pins/ resources?

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Re: Motor Shield V1 & GPS Shield

Post by adafruit_support_bill »

Yes, there are a number of pin conflicts between those two shields:
https://learn.adafruit.com/adafruit-motor-shield/faq
https://learn.adafruit.com/adafruit-shi ... gps-shield

The V2 motor shield uses only SDA and SCL, so it has no conflicts with the GPS shield.
https://www.adafruit.com/product/1438

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Re: Motor Shield V1 & GPS Shield

Post by project_science »

That is interesting and explains the funky behavior. Thank you.

do you know if the GPS of V2 motor shield would have conflicts stacked with the wireless shield (which I'm currently using?)
http://arduino.cc/en/Main/ArduinoWirelessShield

I haven't seen any issues, just wondering if I'm missing something before upgrading to the V2

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Re: Motor Shield V1 & GPS Shield

Post by adafruit_support_bill »

I don't see any pin conflicts there.

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Re: Motor Shield V1 & GPS Shield

Post by project_science »

Ok, I switched to the UNO, but I don't really see the issue with the stack as it doesn't look like the pins are conflicting (perhaps you can fill me in if I am missing something).

Wireless Shield (using XBee Series 1, no SD card in use): RX,TX (assuming 0,1)
http://arduino.cc/en/Main/ArduinoWirelessShield

Motor Shield v1: 3,5,6,11
https://learn.adafruit.com/adafruit-motor-shield/faq

Ultimate GPS Shield (no SD card in use): 7, 8 (RX, TX) when using Soft Serial
https://learn.adafruit.com/adafruit-shi ... gps-shield

These shields don't seem to have overlapping pins. And they seem to leave these pins open:

2,4,9,10,12,13

So why would the motors be acting funny when using the Ultimate GPS Shield in the stack with the UNO? What could I fix?

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Re: Motor Shield V1 & GPS Shield

Post by adafruit_support_bill »

Pins 4, 7, 8 and 12 are used by the motor shield also.
What pins are not used on the motor shield?
All 6 analog input pins are available. They can also be used as digital pins (pins #14 thru 19)
Digital pin 2, and 13 are not used.
The following pins are in use only if the DC/Stepper noted is in use:
Digital pin 11: DC Motor #1 / Stepper #1 (activation/speed control)
Digital pin 3: DC Motor #2 / Stepper #1 (activation/speed control)
Digital pin 5: DC Motor #3 / Stepper #2 (activation/speed control)
Digital pin 6: DC Motor #4 / Stepper #2 (activation/speed control)
The following pins are in use if any DC/steppers are used
Digital pin 4, 7, 8 and 12
are used to drive the DC/Stepper motors via the 74HC595 serial-to-parallel latch
The following pins are used only if that particular servo is in use:
Digitals pin 9: Servo #1 control
Digital pin 10: Servo #2 control

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Re: Motor Shield V1 & GPS Shield

Post by project_science »

Ok, so if I have this right, using the v2, from your earlier post, would mean that pins 7,8 would now be open (for the GPS) since v2 only uses the SDL / SCL lines? Is this correct? I'm confused by this vs. the pins used listed on the page - unless that page is for v1 only.

I would put the GPS on direct (0, 1), but the wireless shield uses them I think.

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Re: Motor Shield V1 & GPS Shield

Post by adafruit_support_bill »

That page is from the V1 motor shield tutorial and applies to the V1 shield only. The V2 shield has a completely different design (and tutorial to match)

https://learn.adafruit.com/adafruit-mot ... rduino/faq
What pins are/are not used on the motor shield?
The shield uses the SDA and SCL i2c pins to control DC and stepper motors. On the Arduino UNO these are also known as A4 and A5. On the Mega these are also known as Digital 20 and 21. On the Leonardo these are also known as digital 2 and 3. Do not use those pins on those Arduinos with this shield with anything other than an i2c sensor/driver.

Since the shield uses I2C to communicate, you can connect any other i2c sensor or driver to the SDA/SCL pins as long as they do not use address 0x60 (the default address of the shield)

If you want to use the servo connections, they are on pins #9 and #10. If you do not use the connector then those pins are simply not used.

You can use any other pins for any other use

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