I've only used the TT4427 as a MOSFET driver; that said, I've seen several applications where they're used as a half-bridge for small motors. The point is that the device can sink or source 150mA at the VCC voltage which -- I believe -- will allow it to provide enough current to charge the power supply inside the Firecracker. I'm finishing up some client code today and will try to get my Firecracker hooked up after.
I can't believe that the Firecracker would require much current, after all it is being driven directly from a STAMP pin, approx. 20ma max, correct? I have driven lights and relays with the 7406 and it handles a lot more than 20ma. I have a hunch it is a timing issue but I don't have a decent scope to look at the two signals.
I've setup Jon's circuit this morning.. haven't had much luck with it yet. A
Anyone else get this up and running yet?
I suppose another way to tackle this would be to remove the PCB from the shell and bypass the diodes to feed 5V directly to the PIC and see if the inputs respond to the 3.3V signals from the Propeller...
I ordered TC4427CPA (dip version) -- Issue here I didn't realize?
The TC4427A datasheet says:
The TC4426A/TC4427A/TC4428A are improved versions of the earlier TC4426/TC4427/TC4428 family of MOSFET drivers. In addition to matched rise and fall times, the TC4426A/TC4427A/TC4428A devices have matched leading and falling edge propagation delay times.These devices are highly latch-up resistant under any conditions within their power and voltage ratings.
They are not subject to damage when up to 5V of noise spiking (of either polarity) occurs on the ground pin.They can accept, without damage or logic upset, up to 500 mA of reverse current (of either polarity) being forced back into their outputs. All terminals are fully protected against Electrostatic Discharge (ESD) up to4 kV.The TC4426A/TC4427A/TC4428A MOSFET drivers can easily charge/discharge 1000 pF gate capacitances in under 30 ns. These devices provide low enough impedances in both the on and off states to ensure the MOSFET’s intended state will not be affected, even by large transients.
I've posted a photo of my breadboard circuit...
Maybe one of you guys will see where I'm going wrong.. Gotta be a stupid error on my part.
Second pair of eyes anyone?
It works great using my program and Jon's schematic.
If your program is using P0 for DTR and P1 for RTS, you might have your yellow and blue wires on the DSUB connector reversed...
Have you tried my code or just Jon's?
I am feeding 5V to the IC - are you trying to use 3V?
Yeah, I'm using 5v.
I've reversed the DSUB connections just to see if it makes any difference. No dice.
OBCCode:dtr = 0 'DB9 pin 4 on Firecracker rts = 1 'DB9 pin 7 on Firecracker
Rebuilt the circuit again with another batch of parts...
Still no joy..
I've tested the firecracker on the PC, slow but works. Also running your code..
I'm starting to have some real doubts about these chips.
Edit: removed the cap from the 2nd circuit. things starting to happen..
Uncrossed eyes.. pulled everything and rewired the original GG circuit.. Success!
Starting to think I was also being foiled by a broken wire..
Now it gets interesting...
Well I guess I'll have to order a few TC4427 chips.. Where are you guys getting them from, Digikey?
The page is being served by the E-Net module running a modified copy of Harrison's code.
Too bad I can't get status data back from the firecracker...