PIC questions

D

dave.harper

Guest
I'm switching over to PICs from Basic Stamps due speed, capacity, and
price reasons. I've already purchased a semi-universal programmer, and
am looking a couple good PICs to start with. I was thinking about a
lower end PIC for simple projects, and a mid-range PIC for more
advanced stuff. I has thinking about the 12F629 for the low-end stuff,
and the 16F88 for mid-range stuff. Would these be good PICs to start
with?

Also, apparently these come with their own internal oscillators. Am I
correct in understanding that these will not need crystals unless I
want to clock them at different speeds? Do external oscillators add
any benefit for these PICs? Speed? etc?
Thanks in advance for any insight...

Dave
 
There is a lot of low cost PIC stuff at www.glitchbuster.com
12F629 ----- $1.24
16F88 $3.19
16F628 $2.67

-Bill
 
You can find a lot of low cost PIC stuff at www.glitchbuster.com

12F129 is about $1.24
16F88 ------- $3.19
16F628 ------- $2.67

-Bill
 
On 2 Feb 2005 13:00:49 -0800, Bill Bowden wrote:

There is a lot of low cost PIC stuff at www.glitchbuster.com
12F629 ----- $1.24
16F88 $3.19
16F628 $2.67

-Bill
Click to expand...
And he (Randy) ships fast.
--
Best Regards,
Mike
 
dave.harper wrote:
I'm switching over to PICs from Basic Stamps due speed, capacity, and
price reasons. I've already purchased a semi-universal programmer, and
am looking a couple good PICs to start with. I was thinking about a
lower end PIC for simple projects, and a mid-range PIC for more
advanced stuff. I has thinking about the 12F629 for the low-end stuff,
and the 16F88 for mid-range stuff. Would these be good PICs to start
with?

Also, apparently these come with their own internal oscillators. Am I
correct in understanding that these will not need crystals unless I
want to clock them at different speeds? Do external oscillators add
any benefit for these PICs? Speed? etc?
Thanks in advance for any insight...

Dave
Click to expand...

And if you're looking for an upgrade from PICBasic, check out
http://groups.yahoo.com/group/jallist/ and binaries from
http://sourceforge.net/projects/jal/ - new release Jan 28.
 
Byron A Jeff wrote:

You'll need crystals or resonators for 2 types of situations:

1) You need better performance than the 8Mhz can give you. Both parts
run up
to 20 Mhz with an external oscillator.

2) You need tighter frequency tolerances for the USART for example.
Click to expand...
Thanks Jeff. As a follow-up, will the internal oscillator be good
enough for serial communication up to, say, 9600 bps? Under what
circumstances would I need tighter tolerances for the USART?

Thanks again,
Dave
 
In article <1107524967.547926.255080@z14g2000cwz.googlegroups.com>,
dave.harper <dave.harper@gmail.com> wrote:
<
<Byron A Jeff wrote:
<
<> You'll need crystals or resonators for 2 types of situations:
<>
<> 1) You need better performance than the 8Mhz can give you. Both parts
<run up
<> to 20 Mhz with an external oscillator.
<>
<> 2) You need tighter frequency tolerances for the USART for example.
<
<Thanks Jeff.

No problem.

< As a follow-up, will the internal oscillator be good
<enough for serial communication up to, say, 9600 bps?

No promises. It can fluctuate as much as 10% IIRC. Which means that it may
not work.


< Under what
<circumstances would I need tighter tolerances for the USART?

You have a 5% overall error budget between both ends. Anything outside of that
will cause errors.

BAJ
 
Under what circumstances would I need tighter tolerances for the
USART?
Click to expand...

I've used the 16f628 serial I/O at 19,200 with the internal 4 mHZ
oscillator without errors. If the oscillator changes frequency
by 1 part in 18, you lose the last data bit. 1 part in 16 loses
bits 6 and 7, etc. But the internal oscillator seems to be
pretty good at 1% or better. I think I put the circuit in the
freezer, and then under a heat gun, and it survived both tests.

-Bill
 
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