replacing a PIC18F452 by a PIC18F4685

MIOS programming (C)
1

Hello, guys.

I have a finished C application running on a Core + Bankstick + Unmuxed AIN + DIN module.

See http://www.midibox.org/forum/index.php?topic=9495.0.

I run out of memory, so I cannot keep on expanding the application.

So I am thinking of replacing my PIC18F452 by a PIC18F4685 to get more application memory space.

Will my C application work just by recompiling it?

Thanks in advance,

Canrull.

2

4620 would probably be a better solution unless you want CAN.

You don’t even need to recompile to change PIC, but if you want to use the additional RAM you will need to edit the linker script (project.lkr)

I have written lots about that topic before, so now that you have the right search term, I’ll leave you to it. Hint: Check the wiki. :slight_smile:

3

I already searched the wiki, but I didn’t find an unequivocal statement saying it would work… maybe I am a little bit clumsy.

In fact, I saw the thing about the 4620 bug, that will bring me problems with MIDI, because MIDI IN/OUT can happen at the same time, and I am not (and I will not be) using MBHP_IIC_MIDI:

http://www.midibox.org/dokuwiki/doku.php?id=mios_pic18f4620

So I was wondering if using PIC18F4685 was the solution.

Regards,

Canrull

4

Using PIC18F4620 – How to use the newer PIC18F4620 with a lot more cool features together with MIOS v1.9

Using PIC18F4685 – How to use the newer PIC18F4685

5

I already searched the wiki, but I didn’t find an unequivocal statement saying it would work… maybe I am a little bit clumsy.

That’d be because noone has done it before - if you write the document then the next guy won’t have the same problem :wink:

In fact, I saw the thing about the 4620 bug, that will bring me problems with MIDI, because MIDI IN/OUT can happen at the same time, and I am not (and I will not be) using MBHP_IIC_MIDI:

In that case 4685 would be suitable. Note that it does not have as much RAM as a 4620, and that some sections of RAM are not accessible by indirect addressing.

6

Thanks, stryd_one, for your kind response.

I’ll order the new PIC and see if I can manage to make it work.

Regards!

7

No sweat mate, give me a yell when it arrives and I’ll give you a hand if you want :slight_smile:

The linker script may simple but handling the ram correctly could be tricky. I need to go read the datasheet. again. ugh. ::slight_smile:

8

Hi,

old thread but same request.

Is there any linker script for PIC18F4685?

Where to find sdcc’s pic18f4685.h header or can I still compile within pic18f452.h, if I need only more space for coding instead the new abilities of that Chip?

And as an Hardware Option: Can I configure and use LCD connections like before I had used for the PIC18F452 in (8 bit Mode), because i don’t want use CAN Support. Do I have to configure it anywhere?

Greetings,

rio

9

ok, i have found out by myself, when I have looked at http://www.ucapps.de/mios/sdcc_skeleton_v1_1.zip and using SDCC 2.8.0.

It was long time ago, I did notice the changes..