Crystals

[jason]

ok ya your right, on page 61. But WOW what a difference it draws between 4mhz and 20 mhz. If I go with 4mhz I would save alot even if I do only wake up once every 3 seconds or so.

The reason I'm useing this chip, well I dont need any options other than a voltage detector to determine when the power drops to 4.5v and I was using a voltage detector with a trigger at 4.5v. the chip I'm using cost $1.38 (the cheapest I found with 33 ios) here in mexico through newark. Do you know of other pics cheaper that are Flash ? I'm open to suggestions But I do preaty much have my board desgned.

[skimask]

ok ya your right, on page 61. But WOW what a difference it draws between 4mhz and 20 mhz. If I go with 4mhz I would save alot even if I do only wake up once every 3 seconds or so.

Power usage 'generally' goes up as the square of the operating speed...
i.e. 1mA @ 4Mhz, 4mA @ 8Mhz, 16mA @ 16Mhz, etc.etc...not always true, but generally.

The reason I'm useing this chip, well I dont need any options other than a voltage detector to determine when the power drops to 4.5v and I was using a voltage detector with a trigger at 4.5v. the chip I'm using cost $1.38 (the cheapest I found with 33 ios) here in mexico through newark. Do you know of other pics cheaper that are Flash ? I'm open to suggestions But I do preaty much have my board desgned.

If you've got the board designed and have it set up for an 'F59, then switch over to an 18F4620 (or even a 16F877). A bit more spendy, but loads more options, it'll plop right into the same socket with very few (if any) hardware changes, less current draw both in operation and standy with more options to run the clock, including clock switching in the middle of operation, and most importantly...interrupts that can wake up your PIC ONLY when a switch is tripped (see Interrupt on Pin Change in the datasheets for the above mentioned PICs), thereby meaning your PIC would be asleep EXCEPT when triggered by a door...which could mean that practically 99.9999999999% of the time, your PIC is sleeping. And I'd be willing to bet that the difference in price would more than make up for the new-found flexibility of the newer chips.

[jason]

Ya there alot more spendy. I'm trying to keep the cost down to minimal. here in Mexico in Newark the current chip is $1.38 and the 18F4620 is $7.28

However the PIC16F877A-I/PT is $5.70 and if I use a AD for the voltage detection which will save me about $2 that brings me down to $3.70, still a bit more. But like you say the added options. I will think about it.

[skimask]

Ya there alot more spendy. I'm trying to keep the cost down to minimal. here in Mexico in Newark the current chip is $1.38 and the 18F4620 is $7.28. However the PIC16F877A-I/PT is $5.70 and if I use a AD for the voltage detection which will save me about $2 that brings me down to $3.70, still a bit more. But like you say the added options. I will think about it.

One other thing to note...
The PIC16F59 is a 12-bit device, not a 14-bit device like the F877, or 16-bit like the 18F4620.
Using PBP, you'll be limited as to which commands you can use with the 16F59.
Maybe check out the 18F4410/18F4510. Looks to me like they might be a bit cheaper than the 16F877A.

[jason]

Yep I see it now. I went to PBP manual on 12bit core and It wont allow the serin2 command which I need and several other stuff.

those last 2 chips you sugested, newark down here dosn't have them instock, not to mention they are around $7.50

the PIC16F877A-I/PT QTFP 44 pin is in stock and costs $5.70, I just ordered 4 for now, just to have in stock here at the office. But isnt there another chip with a few less features that is cheaper ??? I really liked the $1.38 price sticker cuase I'll be making a few thousand of these cards. There for accounting and security of video arcade games.

[skimask]

the PIC16F877A-I/PT QTFP 44 pin is in stock and costs $5.70, I just ordered 4 for now, just to have in stock here at the office. But isnt there another chip with a few less features that is cheaper ???

Quantity 1000 should get you a decent price break...

< pic16f877a? PIC16F874...1/2 the flash, 1/2 the eeprom, 1/2 the ram, same # of I/O's... PIC16F870, 871, etc,etc.
Go to Microchip.com and do a parametric search...find the chip YOU want. Only takes seconds...
Why so many I/O?

[jason]

The PIC16F914-I/PT is a good price and it has a PLVD module which would save me $2. Just need to figure out how to use it

It also talks about a "Precision" internal Oscillator. Is this good enough for serial comunications in picbasic pro? That would save me another $0.50

Thanks for the tip on the Parametric search at microchip.

[BrianT]

I run a PIC16LF877A with a 3.6 volt lithium battery and a 4 MHz crystal. The crystal costs $0.50. It works just as well with or without the 10 pF crystal caps. Current draw in sleep is under 8 uA. The unit wakes frequently (via the SLEEP nn command) and runs for over a year on a Tadiran TL-5186 lithium button cell. A 16F877A runs close to the same current on 5 volts and also works down to about 3 volts.

HTH
Brian