Migration 18F452 --> 18F4620

[NavMicroSystems]

On one of my projects I'm running out of CodeSpace and Memory.

Having had a look at the 18F4620 I thought it would be a nice replacement.
(twice as big in terms of CodeSpace and Memory)

I think it souldn't be much of a problem to migrate from 452 to 4620.

Has anyone used the 18F4620 yet,
or does anyone have experience with this kind of migration?


(I'm waiting for the chips to arrive)

regards

Ralph

[mister_e]

I didn't use the 4620 as now, some comming for me too. I do some test with those 2525. I got problem when using them with PICSTART. I'm not able to erase/program them correctly. This is a know issue by Microchip's team and they're working on a fix for the next MPLAB version... This is what they tell me last 2 weeks. Hopefully i have also a third party programmer :0)

New MPLAB in about 2 week... suppose to ;0)

After an FAST overview on both datasheet i don't see a real big problem to migrate from one to the other. Also, you have an internal oscillator that can be use with the 4620. I'll receive mine in a few.

Good luck, keep us posted on that!

[NavMicroSystems]

Steve,

Originally posted by mister_e
. . . Also, you have an internal oscillator that can be use with the 4620.

yes,
the INTOSC is another feature of the 4620,
but I don't think it'll be of much use.
If your project really requires 64k of code space
it will most likely require clockspeeds higher than 8MHz.

once I have received the chips I'll do some testing
and I'll keep you posted.

regards

Ralph

[ghutchison]

You might want to check out Microchips web site on the errata for the 18F4620, there are quite a few problems with it. The I2C (MSSP), ECCP, Timers 1&2, Interupts do not work properly and the workaround would be difficult to implement in pbp. There is no date of release for a corrected silicon.

[NavMicroSystems]

Hi all,

I have given up on this migration project.

The 18F4620 appears to have too many bugs that can't be worked around in PBP.

And there is currently no Loader Support.

How to develop (and Debug) Code that is 32+ k in size
without having a working loader?

B.T.W.
the 18F4620 appears to be even more sensitive to noise than the 452 already was.

I would wish the Rock-Solid 16F877A had some more Memory!

[mister_e]

It appear than this 'nanowatt' & 18F technology is a real pain now. Here's a few things i've notice.

• 1. it appear to be less noise sensitive on lower supply voltage...
  
  2. using Brown out voltage as low as you can prevent erratic reboot... not better if you don't set any brown out voltage.
  
  3. use a low value resistor to the VCC of the PIC and adding a 22uF tantalum + 0.1 ceramic capacitor between PIC VDD and VSS... it help !
  
  4. I also try with a dedicated voltage regulator only for the PIC... i didn't see any difference.
  
  5. all unused i/o are set as input and tie directly to the ground.
  
  6. Using internal pull-up appear to give some 'erratic' problems too. i use external 1k for now... seems to be more stable than with 4.7k or 10k.

PCB design is a real major cause. On bread board it's often a pain at 20MHZ or higher. Here's a few tips.

• 1. pcb must have many ground plane surface on both side.
  
  2. PIC must be in the center of your design.
  
  3. keep pull-up/down resisor as close as you can of the PIC
  
  4. every filter cap as close as you can... deuuu!
  
  5. if you can, solder a ground to the crystal casing

[NavMicroSystems]

Steve,

here is one hint you missed:

Do not use any 18F if a 16F would fit

[ghutchison]

I have moved from the 452 to the 4620 with only a few minor problems. (after a week of misery)

1.comment out config settings in the .inc file and remap the memory in the .bas file for picbasic pro.

2. make a small change to the portA settings in my code, as the 4620 has a different width.

Other than that it works well, as far as I can tell. I2C worked without any mods, not using PWM so don't know about that. Code's up to 37k now, 20Mhz,32bit math, multiple menus, LCD, HSER, Membrane keypads, interupts etc...

Chips from Digikey, $1 more than the 452 for an extra 32k code space, not a difficult decision.

need any help, let me know

[k3nshiboi]

I have moved from the 452 to the 4620 with only a few minor problems. (after a week of misery)

1.comment out config settings in the .inc file and remap the memory in the .bas file for picbasic pro.

2. make a small change to the portA settings in my code, as the 4620 has a different width.

Other than that it works well, as far as I can tell. I2C worked without any mods, not using PWM so don't know about that. Code's up to 37k now, 20Mhz,32bit math, multiple menus, LCD, HSER, Membrane keypads, interupts etc...

Chips from Digikey, $1 more than the 452 for an extra 32k code space, not a difficult decision.

need any help, let me know

Hi i am from singapore, currently working with a team of members on the zigbee kit with pic18f4620 controller. We had some codes that we done done on 18f452. We need to migrate the codes from 18f452 to 18f4620. How should we do it? can someone in here guide us please?

we are also using Hi-tech C languages on this programming schemes, so if possible, some guidance or source codes is needed too. Thx

[IMADK]

I am working with PIC18F4620, and can not seem to get the input to read high. I simply made a small program with proper 2.2K pull down resistor on PortC.4, as input, and wanted high on PortC.1 or PortC.3 when input is high. Very simple .

I noticed that when I push a small switch (connected to +5 VDC) to PortC.4 the program switches a small LED on on PortC.1. But when I removed the +5 V from PORTC.4, the output remains high. The only way it will go low again, is if I wait for 1 or 2 minutes, or if I short PortC.4 to ground. Any ideas.

This is one of my easy problems, I am having more problems like LCD freeze after a day or two of testing. And such.

[IMADK]

I am working with PIC18F4620, and can not seem to get the input to read high. I simply made a small program with proper 2.2K pull down resistor on PortC.4, as input, and wanted high on PortC.1 or PortC.3 when input is high. Very simple .

I noticed that when I push a small switch (connected to +5 VDC) to PortC.4 the program switches a small LED on on PortC.1. But when I removed the +5 V from PORTC.4, the output remains high. The only way it will go low again, is if I wait for 1 or 2 minutes, or if I short PortC.4 to ground. Any ideas.

This is one of my easy problems, I am having more problems like LCD freeze after a day or two of testing. And such.

[Dave]

IMADK, Are you sure the resistor is connected? It sounds like the input is floating. Check it with a meter when the switch is open....

Dave Purola,
N8NTA

[bluestar84]

Iam having similar problems with the 4620 the PORTA seems not to work as an input and I checked the high signal, it seems I have to set some configuration bits, can anyone show me his initialization and the #pragma derctives he used? thanks karl

[mister_e]

for sure those will work if you're using I2CREAD of PBP... that's for sure. BUT if you use the internal MSSP module... that's a real pain. OR if you're going to use thos 18Fs in a noisy environement... can caused you some headaches.

Sometime we need to use the internal ressources to save code space or have more speed/flexibility. I'm actually working on a project with a PIC18F2525 48K of code space as MASTER MCU to interface more than 550 i/o(as now... customer ask for more every day) + graphic lcd + a stack of external EEPROM + serial com to/from a external PC for CD burner and other stuff + joystick + Motorized faders and pot + + + + + +... i'm now close to the end of the available code space. i'm using most of the internal ressources with problems with MSSP and the internal Multiplier. If i change for PBP statement... it works as i need to, SO i'll have to change to PIC18F2620 to have 64K of code space wich i consider it CAN BE enough... as now.


BTW 18F is still new on the market and i think/hope they will improve them.