8-bit vs-16 bit PICs... - Electronic Circuits Projects Diagrams Free

smanches · 26th March 2009, 10:12 PM

After reading these forums for the past month, I've noticed there is never a mention of using the 16-bit PICs, only ever 8-bit versions. I was wondering why this is?

I've been using the 24H and 33F series almost exclusively. For my ACIM control the 33F MC series has a full H-bridge PWM controller with separate PFC PWM controller built in.

I could see using the smallest common denominator in a comercial product that is mass produced, but for hobby/one-off projects, I've always thought the bigger/better/faster controller would give more flexibility in the design process.

**Nigel Goodwin** · 26th March 2009, 10:16 PM

Generally an 8 bit PIC is already massive overkill for most projects - so why spend more money on even more massive overkill?.

dknguyen · 26th March 2009, 10:18 PM

Most people asking PIC questions are blindly following manuals and other people's older designs which are using 16Fs, not even 18Fs.

blueroomelectronics · 26th March 2009, 10:28 PM

Or worse the ancient 16F84
8 bit Micros are still huge sellers and still the least power hungry.

smanches · 26th March 2009, 10:29 PM

It could just be that I'm a software engineer by trade, so I think in those terms. But also some of the features available are quite handy. Many people here making H-Bridge inverters, but not using dedicated h-bridge controllers.

I'm still depressed there is only one C++ compiler out there and I think it's $5000. And dont' start a C/C++ argument over this, please. I would really love function overloading.

blueroomelectronics · 26th March 2009, 10:34 PM

There are several 8bit PICs that have an enhanced PWM module too. I've used a 24H in a project that used its funky 32/512x PLL as I needed some rather unusual frequencies.

dknguyen · 26th March 2009, 10:52 PM

Quote:

Originally Posted by smanches

It could just be that I'm a software engineer by trade, so I think in those terms. But also some of the features available are quite handy. Many people here making H-Bridge inverters, but not using dedicated h-bridge controllers.

I'm still depressed there is only one C++ compiler out there and I think it's $5000. And dont' start a C/C++ argument over this, please. I would really love function overloading.

*cough* ARM *cough* Oh wait, that's not 16 bit.

3v0 · 26th March 2009, 11:17 PM

Some 8 bit C compilers offer function overloading. I have used it with CCS PWM (16F) and BoostC on 18F chips.

hantto · 26th March 2009, 11:30 PM

I've stuck with the 16-series as I know the assembly quite well. I'm too lazy read up on the few 18-series extra instructions

But I understand that the 18 are meant to be coded in C, and things might change soon as I'm learning C for normal PCs right now at a C-course.

I like the fact that assembly is so near the device itself, it will do exactly what it is told to and I can take a paper and pen and figure out EXACTLY how long a routine will take to execute. And that makes it easier to bit-bang various communications schemes, which makes you a little less dependant on built-in peripherals.

Nigel had a good point which is valid for me, most of the time 16s are more than enough.

C looks nevertheless quite appealing to me. All math operations would be a lot easier.

DirtyLude · 26th March 2009, 11:44 PM

Quote:

Originally Posted by dknguyen

*cough* ARM *cough* Oh wait, that's not 16 bit.

Technically Thumb mode would be 16bit.

Writing code for an ARM, I've gotten into a totally different mindset. Libraries I'm writing are much more full featured and I can write a library that encompasses a 'family' of chips I'm interfacing with rather than just a single chip or device and I don't care so much about the speed/codespace overhead. It also means I'm implementing a lot of error checking and validation that I would not have bothered with where code space was a premium.

3v0 · 26th March 2009, 11:46 PM

It would be unusual for most people to prefer a computer language they did not know. Would you be suprised to find that my favorite spoken language is english ?

People have said C adds a layer of abstraction. It does but that is a very good thing.

I prefer to have to computer hide the details related to its instruction set. It allows me to think at the C level and generate code faster.

When I have to I can write inline ASM or look at the disassembler for details. It does not happen all that often.

I try to stay language neutral. My favorite tends to be the one I am using.

3v0

smanches · 26th March 2009, 11:56 PM

I'm old school from learning to code on 6502's (apples, commodores, atari's), so I think in "high-level assembly" but code in C/C++. If I need to optimize a routine, I usually just start with the compiler output and go from there, as it's going to be very close to what I need. I really don't like writing code if I don't know exactly how the hardware/OS is going to execute it.

I'll have to look into the AVRs. I've done some Gameboy programming, but never realized there were MCU versions of the ARM.

When do you think the MCU market is going to be corrupted by Java?

3v0 · 27th March 2009, 12:35 AM

There are already "embedded systems" capaible of running most any language you like. But they can be expensive.

You can expect to see Java on an increasing number of embedded systems. How far down the chain it will travel will be limited by memory requirements. Sun already has an embedd java if you do not mind running a linux kernel or Windows XP-Embedded.Java SE for Embedded – System Requirements EDIT: It looks like there is no charge for this software.

Most of the code written on 8 and to some exstent 16 bit systems are simple compared a large OS or an accounting system. OO makes a lot of sense for complex applications but there are a lot of applications where OO is overkill, a burden.

On the low end I would look for extended more capable C compilers with features such as function overloading (smanches post). I would not look for, or want, inheritance on these small sytems.

The more capable 16 bit and 32 bit units are another matter. The first compiler I would look at is BoostC++. The memory limited version is free and the unlimited but non commerical use is only $100.

3v0

Ubergeek63 · 27th March 2009, 02:52 AM

Quote:

Originally Posted by smanches

I'm old school from learning to code on 6502's (apples, commodores, atari's), so I think in "high-level assembly" but code in C/C++. If I need to optimize a routine, I usually just start with the compiler output and go from there, as it's going to be very close to what I need. I really don't like writing code if I don't know exactly how the hardware/OS is going to execute it.

I'll have to look into the AVRs. I've done some Gameboy programming, but never realized there were MCU versions of the ARM.

When do you think the MCU market is going to be corrupted by Java?

as a teen I programmed apples, commodores, TI 99/4s, 6800s and more.

there actually are java micros, the arm jazelles have java byte code built in and some are available from NXP and others. We currently have a project quoted that will use a TI ARM 9 video chip that has java code built in.

Dan

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar
Title	Starter	Forum	Replies	Latest
Why do my pics keep going away?	Tableleg	Micro Controllers	10	19th September 2007 12:16 PM
PICs and PWM	philo	Micro Controllers	6	7th February 2007 01:47 PM
What does the A mean in PICs	drrogla	Micro Controllers	15	5th September 2005 03:00 PM
Where to buy PICs in the UK??	2camjohn	Micro Controllers	1	7th March 2005 07:01 PM
Using PICs for GPS	Squintz	Micro Controllers	3	21st October 2003 12:36 PM

26th March 2009, 10:12 PM	#1
smanches	8-bit vs-16 bit PICs... After reading these forums for the past month, I've noticed there is never a mention of using the 16-bit PICs, only ever 8-bit versions. I was wondering why this is? I've been using the 24H and 33F series almost exclusively. For my ACIM control the 33F MC series has a full H-bridge PWM controller with separate PFC PWM controller built in. I could see using the smallest common denominator in a comercial product that is mass produced, but for hobby/one-off projects, I've always thought the bigger/better/faster controller would give more flexibility in the design process.

26th March 2009, 10:16 PM	#2
Nigel Goodwin	Generally an 8 bit PIC is already massive overkill for most projects - so why spend more money on even more massive overkill?. __________________ PIC programmer software, and PIC Tutorials at: http://www.winpicprog.co.uk

26th March 2009, 10:18 PM	#3
dknguyen	Most people asking PIC questions are blindly following manuals and other people's older designs which are using 16Fs, not even 18Fs. __________________ Tanaka Sensei (avatar) says: Please spell it "ridiculous" correctly! Not "rediculous". ^^ Last edited by dknguyen; 26th March 2009 at 10:52 PM.

26th March 2009, 10:28 PM	#4
blueroomelectronics	Or worse the ancient 16F84 8 bit Micros are still huge sellers and still the least power hungry. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com/

26th March 2009, 10:29 PM	#5
smanches	It could just be that I'm a software engineer by trade, so I think in those terms. But also some of the features available are quite handy. Many people here making H-Bridge inverters, but not using dedicated h-bridge controllers. I'm still depressed there is only one C++ compiler out there and I think it's $5000. And dont' start a C/C++ argument over this, please. I would really love function overloading.

26th March 2009, 10:34 PM	#6
blueroomelectronics	There are several 8bit PICs that have an enhanced PWM module too. I've used a 24H in a project that used its funky 32/512x PLL as I needed some rather unusual frequencies. __________________ Bill Smart Kits build Smart People http://www.blueroomelectronics.com/

26th March 2009, 11:17 PM	#8
3v0	Some 8 bit C compilers offer function overloading. I have used it with CCS PWM (16F) and BoostC on 18F chips. __________________ Please post questions to the forums. PM's are for personal communication. BCHS/3v0's Tutorials Junebug USB PIC programmer kit., USB Bit Whacker, The 15 Minute Printed Circuit Board! (+drill time)

26th March 2009, 11:30 PM	#9
hantto	I've stuck with the 16-series as I know the assembly quite well. I'm too lazy read up on the few 18-series extra instructions But I understand that the 18 are meant to be coded in C, and things might change soon as I'm learning C for normal PCs right now at a C-course. I like the fact that assembly is so near the device itself, it will do exactly what it is told to and I can take a paper and pen and figure out EXACTLY how long a routine will take to execute. And that makes it easier to bit-bang various communications schemes, which makes you a little less dependant on built-in peripherals. Nigel had a good point which is valid for me, most of the time 16s are more than enough. C looks nevertheless quite appealing to me. All math operations would be a lot easier. Last edited by hantto; 26th March 2009 at 11:31 PM.

26th March 2009, 11:46 PM	#11
3v0	It would be unusual for most people to prefer a computer language they did not know. Would you be suprised to find that my favorite spoken language is english ? People have said C adds a layer of abstraction. It does but that is a very good thing. I prefer to have to computer hide the details related to its instruction set. It allows me to think at the C level and generate code faster. When I have to I can write inline ASM or look at the disassembler for details. It does not happen all that often. I try to stay language neutral. My favorite tends to be the one I am using. 3v0 __________________ Please post questions to the forums. PM's are for personal communication. BCHS/3v0's Tutorials Junebug USB PIC programmer kit., USB Bit Whacker, The 15 Minute Printed Circuit Board! (+drill time)

26th March 2009, 11:56 PM	#12
smanches	I'm old school from learning to code on 6502's (apples, commodores, atari's), so I think in "high-level assembly" but code in C/C++. If I need to optimize a routine, I usually just start with the compiler output and go from there, as it's going to be very close to what I need. I really don't like writing code if I don't know exactly how the hardware/OS is going to execute it. I'll have to look into the AVRs. I've done some Gameboy programming, but never realized there were MCU versions of the ARM. When do you think the MCU market is going to be corrupted by Java?

27th March 2009, 12:35 AM	#13
3v0	There are already "embedded systems" capaible of running most any language you like. But they can be expensive. You can expect to see Java on an increasing number of embedded systems. How far down the chain it will travel will be limited by memory requirements. Sun already has an embedd java if you do not mind running a linux kernel or Windows XP-Embedded.Java SE for Embedded – System Requirements EDIT: It looks like there is no charge for this software. Most of the code written on 8 and to some exstent 16 bit systems are simple compared a large OS or an accounting system. OO makes a lot of sense for complex applications but there are a lot of applications where OO is overkill, a burden. On the low end I would look for extended more capable C compilers with features such as function overloading (smanches post). I would not look for, or want, inheritance on these small sytems. The more capable 16 bit and 32 bit units are another matter. The first compiler I would look at is BoostC++. The memory limited version is free and the unlimited but non commerical use is only $100. 3v0 __________________ Please post questions to the forums. PM's are for personal communication. BCHS/3v0's Tutorials Junebug USB PIC programmer kit., USB Bit Whacker, The 15 Minute Printed Circuit Board! (+drill time)