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Can anyone recommend a good AVR book...

L

linnix

Jan 1, 1970
0
... for a beginner?

AVR is so simple, you don't need a book. Just get a development kit
and go through some examples on line and off line.
And what's the difference, anyway, between the AVR and the ATxxxxxxxx
series of chips?

Which AT? Generally speaking, ATtiny, ATmega and AT90 are similiar
AVRs.
 
linnix said:
AVR is so simple, you don't need a book. Just get a development kit
and go through some examples on line and off line.


Which AT? Generally speaking, ATtiny, ATmega and AT90 are similiar
AVRs.


Ah, so the AT90Sxxxx series is also an AVR... thought it was something
completely different.

So, about that book... ;-)

Michael
 
J

Joerg

Jan 1, 1970
0
Hello Michael,
Ah, so the AT90Sxxxx series is also an AVR... thought it was something
completely different.

So, about that book... ;-)

Seriously, as Linnix wrote, you may not need one. I started with the TI
MSP430, thought about buying a book but after taking a look at one I
realized how fast some of the contents become obsolete. By the time it's
printed there is a slew of new uC variations that are now used by everyone.

Main things to get started: Learn the design environment, play around,
try to make the blinky-LED work, try to change blink rates or pattern,
load again and so on. Then study the family guide and the data sheet for
a long, long time. After that you know all the assembler words the uC of
choice understands and what they mean. Even if you never do assembler
you need to become familiar with the peripherals on board and how they
can affect or impair each other.

If you really want a book recommendation I'd post again at
comp.arch.embedded where among many uC experts there is also Ulf
Samuelsson from Atmel. I am sure he'd know which books are good. Ulf is
very responsive, I wish TI and others would participate as well.
 
Joerg said:
Hello Michael,


Seriously, as Linnix wrote, you may not need one. I started with the TI
MSP430, thought about buying a book but after taking a look at one I
realized how fast some of the contents become obsolete. By the time it's
printed there is a slew of new uC variations that are now used by everyone.

Main things to get started: Learn the design environment, play around,
try to make the blinky-LED work, try to change blink rates or pattern,
load again and so on. Then study the family guide and the data sheet for
a long, long time. After that you know all the assembler words the uC of
choice understands and what they mean. Even if you never do assembler
you need to become familiar with the peripherals on board and how they
can affect or impair each other.

If you really want a book recommendation I'd post again at
comp.arch.embedded where among many uC experts there is also Ulf
Samuelsson from Atmel. I am sure he'd know which books are good. Ulf is
very responsive, I wish TI and others would participate as well.


Ah ok. (Actually until you mentioned it I didn't even notice linnix
had replied inline to my first question. Sorry 'bout that, linnix.
:)

Was browsing over at amazon.com and was getting worried about some of
the comments the users said...

Michael
 
M

martin.shoebridge

Jan 1, 1970
0
Try avrfreaks.net I think there is a tutorial on there.......
 
R

Rich Webb

Jan 1, 1970
0
Hello Michael, [snip...snip...]
Seriously, as Linnix wrote, you may not need one. I started with the TI
MSP430, thought about buying a book but after taking a look at one I
realized how fast some of the contents become obsolete. By the time it's
printed there is a slew of new uC variations that are now used by everyone.

Main things to get started: Learn the design environment, play around,
try to make the blinky-LED work, try to change blink rates or pattern,
load again and so on. Then study the family guide and the data sheet for
a long, long time. After that you know all the assembler words the uC of
choice understands and what they mean. Even if you never do assembler
you need to become familiar with the peripherals on board and how they
can affect or impair each other.

If you really want a book recommendation I'd post again at
comp.arch.embedded where among many uC experts there is also Ulf
Samuelsson from Atmel. I am sure he'd know which books are good. Ulf is
very responsive, I wish TI and others would participate as well.


Ah ok. (Actually until you mentioned it I didn't even notice linnix
had replied inline to my first question. Sorry 'bout that, linnix.
:)

Was browsing over at amazon.com and was getting worried about some of
the comments the users said...

The AT90-series were the (AFAIK) "original" processors in the AVR
family. That family recently split into the ATmega-series with an
enhanced instruction set (and, generally, larger processors) and the
ATtiny family that is, well, tiny by comparison.

There is some slop-over, with the relatively new AT90CAN128 chip being
an almost identical twin to the ATmega128.

All you really need to get started is, say, an ATmega8, an AVRISP
programmer or the STK500 (if you don't have breadboards and bench power
supplies handy), a copy of the free AVR Studio, and the device manual.
The individual chapters in the manual do a good job of explaining how to
tickle the various peripherals. The on-line help in AVR Studio handles
the assembler and instruction set.

Like Joerg, I typically approach a new processor with the embedded
equivalent of "Hello, world!": get one pin to toggle at an intended rate
using one of the chip's timers and an interrupt service routine. That's
enough to validate that I grok the toolchain, can create a runnable
image and get it loaded, and can sling around the necessary bits to
handle ISRs and I/O. From there, the rest is just coding ...
 
J

John B

Jan 1, 1970
0
Hello Michael, [snip...snip...]
Seriously, as Linnix wrote, you may not need one. I started with
the TI >> MSP430, thought about buying a book but after taking a look
at one I >> realized how fast some of the contents become obsolete.
By the time it's >> printed there is a slew of new uC variations that
are now used by everyone.around, >> try to make the blinky-LED work, try to change blink rates
or pattern, >> load again and so on. Then study the family guide and
the data sheet for >> a long, long time. After that you know all the
assembler words the uC of >> choice understands and what they mean.
Even if you never do assembler >> you need to become familiar with
the peripherals on board and how they >> can affect or impair each
other.Ulf is >> very responsive, I wish TI and others would participate as
well.
Ah ok. (Actually until you mentioned it I didn't even notice linnix
had replied inline to my first question. Sorry 'bout that, linnix.
:)

Was browsing over at amazon.com and was getting worried about some
of the comments the users said...

The AT90-series were the (AFAIK) "original" processors in the AVR
family. That family recently split into the ATmega-series with an
enhanced instruction set (and, generally, larger processors) and the
ATtiny family that is, well, tiny by comparison.

There is some slop-over, with the relatively new AT90CAN128 chip being
an almost identical twin to the ATmega128.

All you really need to get started is, say, an ATmega8, an AVRISP
programmer or the STK500 (if you don't have breadboards and bench
power supplies handy), a copy of the free AVR Studio, and the device
manual. The individual chapters in the manual do a good job of
explaining how to tickle the various peripherals. The on-line help in
AVR Studio handles the assembler and instruction set.

Like Joerg, I typically approach a new processor with the embedded
equivalent of "Hello, world!": get one pin to toggle at an intended
rate using one of the chip's timers and an interrupt service routine.
That's enough to validate that I grok the toolchain, can create a
runnable image and get it loaded, and can sling around the necessary
bits to handle ISRs and I/O. From there, the rest is just coding ...

You can also download a demo version of a C compiler from the
Imagecraft website. It's free for 45 days and then becomes code limited
to 8K which is still fine for the mega8.
 
The latest version of Atmel's AVR development environment works
together with winavr. This means that you can write a C program and
single-step it in the simulator, watching register, memory and i/o port
values.


One thing to watch out for if you use a serial in-circuit programmer -
it is easy to lock yourself out of the device by setting the fuses
incorrectly.

In particular, setting the watchdog timer to "continuous" prevents
reprogramming of the device or even the watchdog fuse!

John
 
S

Simon Dice

Jan 1, 1970
0
I Agree with the others, but If you still want a reference book for
programming in C the AVRs, I can recomend you this one:
Embedded C Programming and the Atmel AVR
Authors are Barnett, Cox &Ocull
you can get it from B&N
 
Simon said:
I Agree with the others, but If you still want a reference book for
programming in C the AVRs, I can recomend you this one:
Embedded C Programming and the Atmel AVR
Authors are Barnett, Cox &Ocull
you can get it from B&N


Ok, thanks for the reference.

I think I'll try and build my own programmer. I'll try the
ATTINY11-6PC: $0.53 each at Mouser. What a deal! At this rate I can
buy more than one, in case I burn it out.

I've found some schematics for a programmer out here:
http://www.serasidis.gr/circuits/avrprog/avrprog.htm

I think the pinout is compatible with the AT90S2323, but I'll check the
data sheets on the ATTINY11 to make sure...

Questions:

1) For the parallel port, is Pin 1 the pin on the upper-left looking
at the Printer Port on the PC, or the upper-left looking at the Printer
Cable (IOW, upper-right looking at the PC)?

2) Let's say I want to make a simple AA battery tester (0 to 1.5 VDC
range), and interface it to the PC via serial port. I know I'll need
an ADC, and I can probably get away with using the one on the chip
(comparator, right?). Anyone have any schematic for building such an
AVR-to-Serial interface?

fwiw, I went over to Borders last night, and even the PIC books didn't
discuss in much detail how to interface with the PC. Just only how to
interface the programmer with the PC. Sheesh.

Thanks!

Michael
 
L

linnix

Jan 1, 1970
0
2) Let's say I want to make a simple AA battery tester (0 to 1.5 VDC
range), and interface it to the PC via serial port. I know I'll need
an ADC, and I can probably get away with using the one on the chip
(comparator, right?). Anyone have any schematic for building such an
AVR-to-Serial interface?

Yes, a Max232

Here is a battery charger with RS232 and LED read out. The LEDs are
time multiplexed and maintain a rather constant brightness across
voltage range of 2.4V to 2.8V (two NiMH cells). It's using the
Atmega169, but should work with 165 (cheaper) as well. The basic
components are:

165/169
Max232 w/ 5 Cs
Analog power filter (L, C and 2 R)
LM317

SMPS is optional
Analog multiplexer is not needed.

http://linnix.com/proto
 
linnix said:
Yes, a Max232

A Maxim part? From previous threads, I think I should stay away from
those...

Here is a battery charger with RS232 and LED read out. The LEDs are
time multiplexed and maintain a rather constant brightness across
voltage range of 2.4V to 2.8V (two NiMH cells). It's using the
Atmega169, but should work with 165 (cheaper) as well. The basic
components are:

165/169
Max232 w/ 5 Cs
Analog power filter (L, C and 2 R)
LM317

SMPS is optional
Analog multiplexer is not needed.

http://linnix.com/proto


Pretty neat! You used a drive bay, huh. I couldn't find the
schematics on your site though. I'm mostly interested in the serial
output circuitry. Is yours a bit-banger?

Michael
 
Ah, I think I'm starting to get it. Use a dedicated RS-232 chip. And
here I was banging my head against a wall trying to figure out how to
build my own.

Well, surprisingly, Mouser actually seems to have a few MAXIM 232s in
stock...

Hmm... if I'm going to use an output chip to control my computer
interfaces, maybe I should just bite the bullet and look for a USB
output chip... any suggestions? ;-)

Thanks!

Michael
 
L

linnix

Jan 1, 1970
0
A Maxim part? From previous threads, I think I should stay away from
those...

OK, I should say TI, ST or Sipex RS232 driver chip.
Pretty neat! You used a drive bay, huh.

Yes, charging batteries while working on the PC, and logging the
charge/discharge behaviours of the cells.
I couldn't find the schematics on your site though.

I don't have one either. I went directly to layout from specs.
I'm mostly interested in the serial
output circuitry. Is yours a bit-banger?

No, the 165/169 has hardware UART on pin 2 (RX) and 3 (TX).

AVR pin 2 to 232 pin 10 and AVR pin 3 to 232 pin 11
 
L

linnix

Jan 1, 1970
0
Ah, I think I'm starting to get it. Use a dedicated RS-232 chip. And
here I was banging my head against a wall trying to figure out how to
build my own.

Well, surprisingly, Mouser actually seems to have a few MAXIM 232s in
stock...

Hmm... if I'm going to use an output chip to control my computer
interfaces, maybe I should just bite the bullet and look for a USB
output chip... any suggestions? ;-)

The AT90USB128 is almost pin compatible with the 165/169/329/649.
Unfortunately, you have to rewire pin 2 to 5 for USB and RS232 to other
pins. Actually, we simply bring out the pins to vias and wire them for
either chip. This is a lousy design by Atmel. I wish there is a
AT90USB128/Atmega649 combo.
 
linnix said:
The AT90USB128 is almost pin compatible with the 165/169/329/649.
Unfortunately, you have to rewire pin 2 to 5 for USB and RS232 to other
pins. Actually, we simply bring out the pins to vias and wire them for
either chip. This is a lousy design by Atmel. I wish there is a
AT90USB128/Atmega649 combo.


Looks like the AT90USB128 is about $14 from Digikey. A (Texas
Instruments!) MAX232 is about $0.90. For a beginner, I think I'll
stick with RS-232. (Should be easier to write the software for the PC
side too.)

Thanks a bunch.

Michael
 
L

linnix

Jan 1, 1970
0
Looks like the AT90USB128 is about $14 from Digikey. A (Texas
Instruments!) MAX232 is about $0.90. For a beginner, I think I'll
stick with RS-232. (Should be easier to write the software for the PC
side too.)

We won't be buying that much, but the qty 10K price is $2 to $3.
 
T

Tim Auton

Jan 1, 1970
0
In sci.electronics.design [email protected] wrote:
[snip]
I think I'll try and build my own programmer. I'll try the
ATTINY11-6PC: $0.53 each at Mouser. What a deal! At this rate I can
buy more than one, in case I burn it out.

The ATtiny11 has no RAM, only registers. C really needs some RAM for its
stack, or you have to do some funky things to make it work at all. You
can't have much fun with just 32 registers to store all your data (this
paragraph contains more than 8x that much data). The small ones really
are incredibly limited.

Best advice for a hobbyist: Buy big. Considering the cost of shipping,
it's a false economy to buy the really low-end chips. You'll end up
making another order very soon when you find your first project is
larger than you expect. What you though was a saving ends up as being
more profit for FexEx.

I'd suggest an ATmega8 (or two) and a few matching sockets - you can
then swap the chip from project to project (no need for the sockets if
you don't plan to solder stuff together yet, a breadboard is one big
socket!). The ATmega8 has a UART, which means it has hardware to make
talking to a PC's serial port easier[1]. It has a good amount of RAM
and flash, which means you can use things like C's printf function to
make life easier (printf and associated gubbins takes up around 2.5K of
flash). It has multiple timers, plenty of pins, PWM and a bunch of other
stuff you'll soon find you want.

[snipped a question]
2) Let's say I want to make a simple AA battery tester (0 to 1.5 VDC
range), and interface it to the PC via serial port. I know I'll need
an ADC, and I can probably get away with using the one on the chip
(comparator, right?). [...]

You can use a comparator (gives a signal when one input has a higher
voltage than the other) as an ADC, but you have to use it to measure the
time it takes for the voltage you are measuring to charge up a capacitor
to some reference voltage. You have to provide the capacitor, reference
voltage, code to time it accurately, coded to turn that exponentially
varying number into a linear voltage and make sure the current you take
charging the capacitor doesn't affect what you're trying to measure
(this method has a low input impedance - it puts a significant load on
what you're measuring, changing it in the process). It takes two pins
and you can only measure one voltage with your one comparator. This is
not much fun, though it can shave a few cents of the price of your
device, which might be worth it if you want to make a million of them. I
doubt you want to make a million of them. Buy a chip with a proper ADC
built-in; no external components, very little code, more accurate
results, multiple inputs which take just 1 pin each and you can connect
the pins directly to virtually anything without it affecting what you
connect to (the ADC inputs have very high impedance). Don't connect the
inputs to anything outside the AVR's supply range (0-5V probably, but
you have some choice in the matter) though, or you'll fry it.

For the battery, connect - to circuit ground, + to an ADC input on the
AVR. The AVR's ADC can then measure the voltage with half a dozen lines
of code. That wouldn't actually make for a great battery tester; there's
more to testing batteries than just measuring the voltage, but that's
another subject.
[...] Anyone have any schematic for building such an
AVR-to-Serial interface?
fwiw, I went over to Borders last night, and even the PIC books didn't
discuss in much detail how to interface with the PC. Just only how to
interface the programmer with the PC. Sheesh.

Best to use the serial port, as that's by far the easiest. You might
need a USB-serial converter if your PC doesn't have serial ports.
Sending raw bytes is most efficient, but you'd then have to write
software for the PC to decode those bytes. Much easier to just buy a
nice big AVR and use printf to send ASCII text, at least at first. You
can then use something like Hyperterminal on the PC and get text output
on screen with minimum hassle. You can do clever, efficient protocols
and squeeze them into the really cheap AVRs when you've learnt some
more.

[1] You will need a MAX232 or equivalent chip to convert the AVR's 0-5V
serial port (UART) signals to the +/- 15V RS-232 signals a PC serial
port expects - remember to buy the 4 capacitors such chips require too,
if you don't have that kind of thing lying around. You need to think
about the cable from the chip to the PC as well.

If you haven't already, check out AVRFreaks. There is a lot more there
than there may appear to be at first.

http://avrfreaks.net/


Tim
 
Tim said:
In sci.electronics.design [email protected] wrote:
-=snip=-

Best advice for a hobbyist: Buy big. Considering the cost of shipping,
it's a false economy to buy the really low-end chips. You'll end up
making another order very soon when you find your first project is
larger than you expect. What you though was a saving ends up as being
more profit for FexEx.

I'd suggest an ATmega8 (or two) and a few matching sockets - you can
then swap the chip from project to project (no need for the sockets if
you don't plan to solder stuff together yet, a breadboard is one big
socket!). The ATmega8 has a UART, which means it has hardware to make
talking to a PC's serial port easier[1]. It has a good amount of RAM
and flash, which means you can use things like C's printf function to
make life easier (printf and associated gubbins takes up around 2.5K of
flash). It has multiple timers, plenty of pins, PWM and a bunch of other
stuff you'll soon find you want.

-=snip=-

Thank you for taking the time to give very good advice to us newbies.
I appreciate it.

I think you're right. ATmega8. For about the price of a Six Dollar
Burger at Carl's.

Michael
 
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