Choose between Raspberry Pi 4B 4GB and ROCKPro64

[Bernd Walter]

On Wed, Nov 13, 2019 at 02:34:44PM -0700, Ian Lepore wrote:
> 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.

Damn - now that is a good explanation.
It is a development board after all and not blindly taking power from
USB makes a whole lot of sense...
Will try that later - thank you for that information.

-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.