Driving multiple servos from the RaspberryPi

[mikerr]

Servoblaster doesn't work with the new Pi 2 , and according to this is a simple change:

Anything which uses userland DMA will require updating above and beyond the peripheral base address move (0x20000000 -> 0x3F00000) to work on the Pi 2.

Looking in servo.d I see

Code: Select all

#define DMA_BASE                0x20007000
#define DMA_LEN                 0x24
#define PWM_BASE                0x2020C000
#define PWM_LEN                 0x28
#define CLK_BASE                0x20101000
#define CLK_LEN                 0xA8
#define GPIO_BASE               0x20200000
#define GPIO_LEN                0x100
#define PCM_BASE                0x20203000
#define PCM_LEN                 0x24

So it should be a matter of editing those to the following and recompiling ?

Code: Select all

#define DMA_BASE                0x3F007000
#define DMA_LEN                 0x24
#define PWM_BASE                0x3F20C000
#define PWM_LEN                 0x28
#define CLK_BASE                0x3F101000
#define CLK_LEN                 0xA8
#define GPIO_BASE               0x3F200000
#define GPIO_LEN                0x100
#define PCM_BASE                0x3F203000
#define PCM_LEN                 0x24

I guess this would make a Pi-2 specific version

[joan]

Servoblaster doesn't work with the new Pi 2 , and according to this is a simple change:

Anything which uses userland DMA will require updating above and beyond the peripheral base address move (0x20000000 -> 0x3F00000) to work on the Pi 2.

...
...
So it should be a matter of editing those to the following and recompiling ?
...

Afraid not. With "will require updating above and beyond the peripheral base address move" I was trying to point out there is rather more involved than just changing a number and recompiling.

[mikerr]

Richard has posted a new pi-2 version here:

http://www.raspberrypi.org/forums/viewt ... 5&start=47

works for me

[raver79]

Hi

I am having a bit of a problem. I have managed to wire up two servos to create a pan/tilt mechanism for my camera. The servos are both moving although one servo moves to the default position before moving to the position i have requested. If i ask it to go to 50% for example it goes to 0% and then moves to 50%. Anyone got any idea how i may be able to solve this problem?

Dean

[joan]

Hi

I am having a bit of a problem. I have managed to wire up two servos to create a pan/tilt mechanism for my camera. The servos are both moving although one servo moves to the default position before moving to the position i have requested. If i ask it to go to 50% for example it goes to 0% and then moves to 50%. Anyone got any idea how i may be able to solve this problem?

Dean

Is this a one-off initialisation problem or does it happen whenever you change servo position?

Anyhow, check your code. It seems unlikely to be a problem with servoblaster.

[raver79]

Hi

It happens whenever i change the servo position

[joan]

Hi

It happens whenever i change the servo position

I've not heard of anything like that before.

Which Pi model and which model of servos?

[raver79]

It's the B+ model. The other servo is fine. I have a feeling that one of them is faulty. I have contacted the seller off Amazon. It's a Tower Pro servo

[ame]

It's the B+ model. The other servo is fine. I have a feeling that one of them is faulty. I have contacted the seller off Amazon. It's a Tower Pro servo

Did you try swapping the connectors over? i.e. drive the 'faulty' servo from the 'good' servo's GPIO?

If the 'good' servo shows the same faulty behaviour, or the 'faulty' servo gets better then you know it's a software problem.

[jcg1541]

Love it. Just don't put it on the transatlantic 747 plane that I will fly to Paris to visit my wife's family.