Moving From PIC18F47K42 to PIC18F57Qxx

soonc · Joined: 03 Dec 2013 Posts: 215

I'm trying to plan a move from PIC18F47K42 to PCI18F57Qxx.

There are two chips that are so similar.

PIC18F57Q83
PIC18F57Q43

The Q83 has JTAG, CAN and More RAM (perhaps other things I have not noticed yet).
The Q43 is more like the 47K42 Same RAM no JTAG or no CAN.

I checked the CCS compiler does support both chips.

The Question/s:

I've never needed JTAG (am I missing something?) and don't plan to use the CAN but like the idea of 4K more RAM.

If I go to the Q83 and never use the JTAG or CAN does it become a problem for Power Consumption, Hardware layout requirements etc compared to the simpler Q43 ?

Thanks in advance for any replies.

Ttelmah · Joined: 11 Mar 2010 Posts: 19504

Jtag gains nothing, since the CCS compiler does not support this.
The basic Q83 chip draws typically about 15% more power when running and
up to about 50% more in some standby modes.
Most of the errata don't look too bad. Nothing in the 'core' operation at
all. Unusual. A couple of ones relating to the timer, that are avoidable.
Both are out of stock from most suppliers at the moment, but the Q43
has the shorter lead time.

temtronic · Posted: Mon Mar 14, 2022 7:09 am

sigh....
Both are out of stock from most suppliers at the moment, but the Q43
has the shorter lead time.

Sadly, sounds real common today...

So does a guy BUY 1000pcs of 'in stock' xxx and cut code to fit ??

newguy · Joined: 24 Jun 2004 Posts: 1907

temtronic · Posted: Mon Mar 14, 2022 9:49 am

Sad thing is you could probably sell off your entire stock of PICs and RETIRE !!!
Course then you'd have to BUY some PICs to play with.... Very Happy

Ttelmah · Joined: 11 Mar 2010 Posts: 19504

Interesting Newguy, you obviously had the same suspicions as me!.

newguy · Joined: 24 Jun 2004 Posts: 1907

Things are only going to get worse. Prior to the end of February, my gut feeling was that the semiconductor shortage would clear in approximately 2024.

Now that about half the world's supply of neon is cut off, I'm done with prognostication. The only sure thing is that rationing will be the new norm moving forward.

soonc · Joined: 03 Dec 2013 Posts: 215

Thanks to everyone for the info.

I have enough 47K42 for this year but I'm seeing the long lead times and if I really have to wait that long I could be developing Rev 2 of my PCB to incorporate some "would be nice if" ideas.

Thanks again for all the info.

Ttelmah · Joined: 11 Mar 2010 Posts: 19504

It's getting more complex.
Older chips that use visible light photolithography, don't need neon.
The very newest chips from people like Intel are using X-Ray litho, and
this again doesn't need neon.
It is the medium/high density chips using UV litho, that lead to a sudden
increase in neon usage, which has been pushing supplies for the last five
years.
Now unlike helium, neon can be produced anywhere. It's done by special
extraction on cryo plants. However the amounts are tiny, and 90% of
cryo companies don't bother. The biggest plant doing this is in Ukraine.
Most chip plants are saying they have perhaps 3 months supplies.
Now adding neon extraction is going to take significant time....