Questions on FLiP

cbmeeks

First of all, love the name and the palindrome 32123.

From what I can tell, it looks like I can power the FLiP from my normal 5V power supply. Which is awesome. So no need to add voltage regulators to go from 5V to 3K3.
Now, I assume this is power only. The I/O pins are still 3K3 volts. Is this correct?

With P26/27 I feel that LED's on them might cause me problems. I actually need MORE than 32 pins so loosing two pins might be a deal breaker for me. Looks like it would be a chore to remove them. Would using those pins for VGA output or bus input (1 MHz) be an issue?

Thanks

tomcrawford

The LEDs are buffered and present essentially zero loading.

Tracy Allen

While the pins don't drive the LEDs directly, there are 65kΩ pulldown resistors as seen in the schematic. By the way, the pdf schematic can be found on the 32123 page under "Diptrace files". Just have to design around the 65kΩ.

cbmeeks

Sorry I'm such a n00b...but what is the purpose of such high pulldown resistors?

If I wanted to attach one of those pins to a chip enable pin of another chip...for example...would that be an issue?

Thanks

Mike Green

The pulldown resistors are high resistance to minimize the current to ground in case the I/O pins (P26 & P27) are set to output high. They're there at all to make sure the LEDs are off if the I/O pins are set to input mode (the default).

If you connect another chip to them, the default settings will be low until the Propeller runs a program to change the I/O settings to something else. This is OK if you connect a true chip enable that turns the chip on when a high signal is present. Many such chips are active low though and will be enabled by default when connected to these pins. Easiest fix would be to use an inverter between the chip enable and these pins.

cbmeeks

That makes perfect sense.

And you are right about the active low...I was just using an example.

I've told my wife I want one of these for my birthday. But looks like they may be hard to obtain later.

Thanks everyone!

Whit

cbmeeks wrote: »

I've told my wife I want one of these for my birthday. But looks like they may be hard to obtain later.

Fear not! They will make more!

erco

Just got my FLIP module. Must. Build. Robot. Question about powering from a Li-Ion battery (4.2V-3.7V)...

Connect to 5-9Vin? Is it a low dropout regulator? What's the overhead voltage?

Whit

erco wrote: »

Just got my FLIP module. Must. Build. Robot. Question about powering from a Li-Ion battery (4.2V-3.7V)...

Connect to 5-9Vin? Is it a low dropout regulator? What's the overhead voltage?

erco - Congrats! Can't wait to see what you build - I believe the answers are here - 32123-Propeller-FLiP-Module-Guide-v1.1.pdf

KeithE

And the schematics are online in the zip file - 32123-FLIP-Rev-A-Schematic-20170505.pdf

VonSzarvas

erco wrote: »

Just got my FLIP module. Must. Build. Robot. Question about powering from a Li-Ion battery (4.2V-3.7V)...

Connect to 5-9Vin? Is it a low dropout regulator? What's the overhead voltage?

Erco- your the man ready for this... You'll need Li-ion twins.

In theory the absolute min vin is 4.5V, plus a load dependent diode drop of about 260 to 400mV. Keep above 4.8V ideally.

erco

Thanks for that info, guys. Since weight's a factor on this one, I need to stick with a single 14500 cell, so I'll have to include a 5V booster. Per Supertramp, it sure seems like the long way home: 3.7V boosted up to 5V, regulated down to 3.3V.