Choose between Raspberry Pi 4B 4GB and ROCKPro64

[Ian Lepore]

On Wed, 2019-11-13 at 22:27 +0100, Bernd Walter wrote:
> On Wed, Nov 13, 2019 at 02:13:20PM -0700, Ian Lepore wrote:
> > On Wed, 2019-11-13 at 21:48 +0100, Bernd Walter wrote:
> > > 
> > 
> > [...]
> > > Ok - the FT4232H mini module won't even probe on USB :-(
> > > I have another FT4232H, which probes fine, but has RS232
> > > transceivers.
> > > A board with - I assume - a genuine CH340G shows exactly the same
> > > problem.
> > > Tomorrow I will hook up a logic analyzer to see what really
> > > happens on
> > > the wire.
> > > 
> > 
> > The 4232 minimodule claims that it needs 150ma, so it fails to
> > attach
> > if connected to a bus-powered hub.  (Maybe it could pull 150ma if
> > all
> > channels were running max speed and driving activity LEDs, but
> > otherwise it more like actually uses 30-40ma.)
> 
> Good point - the hub port is self powered, but it may lie.
> I never configured the module - probably it's not even configured
> into
> UART mode at all.
> but that's not the issue.
> I've retested at another hub port with the same result.
> The other module claims 200mA and probes fine.
> Guess my module is just broken.
> 

Oh, there are wires/pins you have to connect to make the minimodule
work.  From the datasheet, to power the module from the bus with no
independent 5v supply:

1) Connect VBUS to VCC (CN3, pin 1 to CN3, pin 3). This connection
takes the power from the USB bus (VBUS) and connects it to the voltage
regulator input on the FT4232H Mini Module. The voltage regulator, in
turn, provides V3V3, VPLL and VUSB power inputs to the FT4232H chip.

2) Connect V3V3 to VIO (CN2, pins 1, 3 & 5 to CN2, pins 11 & 21 and
CN3, pins 12 & 22).  This connection provides the correct 3.3VDC
operating voltage for VCCIO on the FT4232H chip.

I made the connections by soldering on some 30ga wires on my modules,
but you can just use dupont-wire jumpers to get going.

-- Ian