MultiWii

Just after someone that is a better engineer than me to take a look at something for me.

http://www.pvelectronics.co.uk/index.ph ... ucts_id=64

If I want to add a backup battery to this board can I just attach a coin cell between vback and ground?

Or do I have to do something about the zenor regulator installed to drop my 5v vcc to 3.3v on vback? Do I need to disconnect it?

vback can accept a maximum of +5v, so you should be ok putting a coin cell in circuit.

I don't know what the current draw on vbackup is, but a coin cell may or may not last long.
This is the same GPS module I was looking at and its certainly designed to have 3.3v on vbackup, probably best not to apply more.

refractions wrote:vback can accept a maximum of +5v, so you should be ok putting a coin cell in circuit.

yeah my concern is how the vback is currently tied to the zenor regulator - I think I need to take that out and tie enable to 5v before putting the coin cell in the circuit. But I'm not certain.

yes,remove that.

Pyrofer wrote:I don't know what the current draw on vbackup is, but a coin cell may or may not last long.
This is the same GPS module I was looking at and its certainly designed to have 3.3v on vbackup, probably best not to apply more.

Paul uses a simple coin cell on his gps breakout board. But I know that the Module stops working if it doesn't receive 3v on vback.

I could also use a super capacitor like the Navigtron has. I think this may be the best option.

It's a nice board and the seller ships very quickly. I updated the firmware to 115200 @ 10hz with no problem.

You can have either the diode getting 3.3v from the main power OR a coin cell. Otherwise power is pushed into a non-rechargeable battery, not good. Adding a diode over the coin cell would drop its voltage too low I expect.

A super cap would be better if you want to keep the power from the diode too.

Pyrofer wrote:You can have either the diode getting 3.3v from the main power OR a coin cell. Otherwise power is pushed into a non-rechargeable battery, not good.

yep that was what I thought.

Looking to see if I can find somewhere to get a 0.22uf 3.3v super cap without having to order loads of them.

Then I think I'll do Melih's trick of having a blue LED tied to Vcc 5v before the super cap and then tie vback between those. The LED charges the supercap and then the supercap supplies 3.3v to vback with about a week backup power.

How are you interfacing this to Multiwii? Are you just using the main serial port?

I have a BT dongle on that at the moment and will obviously have to choose which I want... Unplugging all the time to swap between USB, BT and GPS is going to suck.

Pyrofer wrote:How are you interfacing this to Multiwii? Are you just using the main serial port?

I have a BT dongle on that at the moment and will obviously have to choose which I want... Unplugging all the time to swap between USB, BT and GPS is going to suck.

I bought one of those new MEGA2560 based boards that have just appeared from China so I'm not so limited in my I/O choices. I also have the Flytron I2C Navigtron GPS board for my 328 based FCs.

I bought this GPS board specifically to use with my MEGA and potentially also Megapirate code (if I ever get Acro and Stable PID tuned properly)

Hi Katch - could you point me in the direction on how to update the firmware on these GPS modules please?


Regards

griffc

Ahh .. just found it in another (very helpful) post !