May I wired 2 PIC in parallell? I want to use one of them at a time.

[rkhoo]

I have a AstroFlight AF109 Lipo charger. It uses a PIC 16C770 as controller.

I have acquired their new firmware to charge A123 cells.

So I have 2 pic with different firmware: one for lipo and the other for A123.

I want to use the same charger for lipo as well as A123 at difffernt time.

Of cause I can change the PIC chip everytime I want to charge a different battery -- but that is teadious (sp?).

My initial thoughts is: what if I wires both PIC in parallel, i.e. one on top of the other, except the power rails -- where it will be wired to the switch. That way, I can select with PIC chip to power to provide the needed firmware to tun the charger. Will this work?

An other aternative is to wire a ZIF socket from the main board out the chasis. I can then change out the PIC as needed. I do not ike the exposed PIC chip though. I am also concern about interference due to the ground plate of the main board will be far away from the ZIF socket (2 inches).

Please help.

(I have also posted on the DIY and battery section.)

Ronald

[AndyKunz]

No, the chip will power up through the I/O pins. I used this once to allow the chip to be plugged into a circuit "backwards". The boot code would look at the I/O pins and set them appropriately. The VSS and VDD pins were left unconnected.

The other problem you will have is loading on the xtal. You could connect multiple PICs in an oscillator daisy chain (OSC1/OSC2 connected to xtal on PIC1, with OSC2 of PIC1 connected to OSC1 of PIC2, OSC2 of PIC2 to OSC1 of PIC3, ...

The distance to the socket might make a difference with the analog sense pins.

Why not just buy a second 109?

Andy

[Ron W3FJW]

Don't they have a software download for the new firmware that would include A123 cells ?

[Dan Baldwin]

They do not have one chip that will charge both LiPos and A123s. You have to choose which you want to be able to charge.

Dan

[Mr.RC-CAM]

Seems doable. I suggest wiring them up in parallel, including power, but exclude the OSC pins and MCLR. Each pair of OSC pins would get their own xtal. However, if the internal 4Mhz Osc is being used then the external OSC pins should be tied together (because they are probably I/O in these situations).

To choose which PIC to run, you would set the MCLR pin high on the chip to use.

[Dan Baldwin]

That would work fine, unless the MCLR pin is set in the configuration word as a digital input instead of MCLR. I think it is.

Dan

[SteveM732]

Why not just buy a second 109?

Andy
Astro Flight seems a little short sighted and a little slow to embrace new chemistries and those who want one charger for multiple chemistries. I think the OP would be better served by a LiXX capable charger which Astro Flight fails to offer.

[rkhoo]

That would work fine, unless the MCLR pin is set in the configuration word as a digital input instead of MCLR. I think it is.

Dan

RC-CAM's idea seems to work but Dan you seems to know the MCLR pin of AF109 is being ued for INPUT rather than MCLR. Can you confirm?

I have followed Pat's mod on the AF109. However I liked the 60 seconds stage1 of the A123 mode better. The A123 firmware will also supoort 10S A123.

[leu1]

Load different code to one PIC at different time.

[rmteo]

Load different code to one PIC at different time.
A PIC16C770 (which is OTP) won't allow this.

[Tomapowa]

Load different code to one PIC at different time.

Code (hex) is also protected... so I believe...

[ZAGNUT]

same question came up years ago and the only solution was to switch all the pins. since the pic's internal oscillator is used it was pretty straightforward.

http://www.rcgroups.com/forums/showthread.php?t=271622&highlight=pic16c770

[rkhoo]

Thanks ZANUT, from that thread it seems everyone is agreed that the MCLR is not used as reset and Astro uses the internal OSC.

So that left me with ZIF sockets or a printer DB25 big switcher :(