View Full Version : 44-PIN QFP Wiring

10-21-2011, 07:42 AM
I finished a program that I would now like to use in a remote device.
The program was written using the 40-pin DIP PE-kit during development, but for size reasons I am going to use the 44-pin QFP in the final device.
I am a little curious about the extra pins on the 44-pin LQFP, I could not find answers for all my questions in the prop manual or spec sheet.

Does the 44-pin use the same voltage regulators and capacitors as the 40-pin?
Do all four of the VSS & VDD pins need to be connected?
Do the propclip TX & RX connections still go to pins 30 & 31 respectively?
EEPROM SDA * SCL connections still go to pins 29 & 28 respectively?
So basically do I wire this up exactly as the 40-pin DIP but add the extra VSS & VDD pins?


Peter Jakacki
10-21-2011, 07:57 AM
First off, don't confuse pin numbers with port numbers pin 30 is not the same as port 30 etc. The DIP40 is a little bit crippled really as the long leads in the lead frame are less than optimal and it only connects to two each of the power and ground. I'm not sure if it may be "jumpered" internally but the chip itself is a "44 pin" chip if you like. Always connect up all the VSS together and VDD together and use decoupling caps on all 4 sides unless you know what you are doing.
Anyway, the time honored advice is RT*M, that is the hardware DATASHEET itself. (I didn't have an expletive to delete but I wanted to keep it recognizable :) )

10-21-2011, 08:02 AM
Shortly... yes.
Consider you have not only to connect all the GND and VCC pins, but you are supposed to add a filter capacitor close to each Vcc/GND pair. (0.1uF is usually a good value).
Check the forum, filter capacitors have been discussed at lenght and are necessary not only for the prop but also for all the other chips.
And don't forget to verify/cross check the pinout with the datasheet..

10-21-2011, 10:39 AM
Thanks Max, I just needed to make sure... I did not think to add filter caps on all 4 sets... will do.
peter... On page 4 I found the general info for the pin ID's... but it does not mention any difference between the DIP40 and QFP44 even though there are more pins.
This is why I wanted to confirm whether it really is the same and wired identical, or if there were differences inferred that I wouldnt know.... such as adding filter caps to all four outputs.
Had I not asked, I probably would have just done 2. Better safe than sorry ya know?

10-21-2011, 10:48 AM
They both use the same chip, internally. Apart form the packaging, they are identical.