I/O Expansion Shield V7 for Arduino

userHead natjking 2014-03-06 01:53:01 6610 Views7 Replies

I am building a robot and was looking at the I/O expansion shield V7. What I would like to do is to be able to grab a lot of input data from multiple sorces such as PING but more improtantily I wish to also be able to drive and control to servers for a tilt pan setup. I think I am correct in saying with the older v5 I could add an extra power source for servos. I think this is also true for v7. What I am struglling to grasp from the documentation is this, the terminal that is denotead servo power is that input or output powr? If I were to connect 2 servos to this board is there an option to just plug it into one of the 3 pin pins if that makes sense and the power comes from there (is this power coming from the additional power source or from the arduino) I ask this as I read someone saying somewhere that you would have to strip the wire from the servo and plug the ground and vcc into the servo terminal and the data wire into the relevent pin. But this is not what I am looking for I would ideally want to plug the 3 pin connector into the board rather than canibilising it. I already own a cheaper IO shield and it is this ability to plug and play but boost the power that I am looking forward.

Any help on the above would be appreciated,

2016-02-16 11:42:31 Hi ntushar,


I've just confirmed with the disigner of the schematic and got this.

(98.58 KiB) Downloaded 661 times

PWR_IN is power for Arduino card under the expansion shield, so it depend on the arduino power requirment, generally speaking, that's 7-12V, and it will be transformed to 5V or 3.3V. e.g. UNO, on this expansion shield, it offers a switch pin for you to choose what kind of voltage you want to use, 3.3V or 5V.

SERVO_PWR is for drivering servos, they are connected to digital pins' power interface directly, so it depends on the servo you use, generally speaking, that's 4.8 - 6V(Usually, servo/ motor requirs large current supply, a >1A/2A power source is good)

And btw, it should be noted that if you apply a power 5V for servo, all the digital power pins will be 5V, if you have sensors that is only 3.3V compatible, you can NOT use it on digital pins, or it will burn, please apply it to analog pins instead. See how to use analog pins as digital one
ntushar wrote:What is the voltage range for PWR_IN and SERVO_PWR. The schematic does not show it
userHeadPic Leff
2016-02-15 03:25:48 What is the voltage range for PWR_IN and SERVO_PWR. The schematic does not show it userHeadPic ntushar
2014-11-17 12:20:23 No, PWR_IN is connect to VIN directly, so if you plug them together, it will be a power issue.

But Servo_PWR is different to the PWR_IN. there is a power chip to regulate Servo_PWR. It will change power resource, when it detect plugged Servo_PWR.
Maybe it will be a little confused.
userHeadPic Grey.CC
2014-11-15 00:58:29 So just to get this correct can I also plug power in to the pwr_in and the arduino vin at the same time or is that bad for the boards?

If there is connected to the Servo_pwr then I would understand the above to be correct but without something connected to the servo_pwr will that mean I have two power sources in parallel and what are the consequences?
userHeadPic natjking
2014-11-14 10:40:50 Hello Natjking,

Pwr_IN is connect to Arduino Vin directly. so if you hook up a power resource. It is same to connect Arduino Vin.
But if you connect Servo_PWR, it will power servo only.
userHeadPic Grey.CC
2014-11-14 05:41:09 Hi Sorry finally got back to some robotics thanks for the previous reply several months ago.

I am trying to understand this board a little bit more. So if I hook up a power source to the pwr in. Does that extra power go to all the pins or just the servo terminal?

If I am powering from the arduino as well what power goes where? Sorry I am new to electronics and don't really understand the schematics yet.
userHeadPic natjking
2014-03-07 16:40:53 Welcome Natjking,

The power in connector is to supply external power to the pins. If External power supply is connected, the servos will be powered from PWR IN. There is no need to canibilising. What cheaper IO shield are you using? maybe works in a different way?

userHeadPic Jose