AVR-Chat

If you post the c source and state that " No one can reduce this program by 10%", you will have a half dozen edits that reduce the program size by 10% in a couple of hours.



-----Original Message-----
From: Chuck Hackett <egroupscdh@up844.us>
To: AVR-Chat <AVR-Chat@yahoogroups.com>
Sent: Sun, Jan 29, 2012 3:57 pm
Subject: [AVR-Chat] Need confirmation on ATMega upgrade path


I designed a board for my railroad signaling project (outdoor, ride-on,
/8th scale) around the ATMega32A and so far it has worked out well running
y multi-node CAN network based system.  
One of the regrets I have is that I did not take the advice of those that
ecommended that I go with an ATxxx-CAN device rather than a non-CAN device
nd an external CAN controller (I chose the MCP2515).  At the time I was not
ure that CAN would work for me so I wanted to keep my network options open.
AN has been working great and I wish I was interfacing with an internal CAN
ontroller rather than having to deal with the extra SPI communications
ayer … live and learn :-)
My other regret Is that I violated a rule I should have known - use the
evice with the largest reasonable amount of memory available to reduce the
hances of "hitting the wall" in development.  Even though this was my first
eal microcontroller-based design, I should have known better ... (see my
ignature line!).
My board is designed around the ATMega32A and I am about at its memory
imits (with optimization turned on) and I have more features to add
naturally).  I would like to upgrade to the largest compatible processor
hat:
 5v supply
 TQFN-44 package
Pins/peripherals I'm using (from memory without detail checking of the
ode):
 8 A/D inputs
 SPI
 TWI
 1 UART (diag & monitoring)
 JTAG
 OC2
 INT2
 AREF
 6 general I/O
 Timers 1&2
 14.7456 Xtal
 Watchdog
I have checked the data sheets and it looks to me like I can choose from the
ollowing:
ATMega644, 644P, 644PA, 644A
TMega1284 & 1284P
Mouser does not seem to stock the ATMega1284x in TQFN-44 but DigiKey stocks
he ATMEGA1284P-AU-ND which would seem to fit the bill.
For my use is the ATMEGA1284P-AU-ND pin and software (with appropriate
hanges in defines, etc.) compatible the ATMEGA32A-AU or am I missing
omething?
Thanks in advance for any help you can provide ...

heers,
Chuck Hackett
Good judgment comes from experience, experience comes from bad judgment"
.5" gauge Union Pacific Northern (4-8-4) 844
ttp://www.whitetrout.net/Chuck



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