Using Cheap Asian Electronic Modules
By Jim Rowe
USB-PD Triggers,
Decoys and Testers
Left-to-right: the FNC88, WITRN UPD005, ZY12PDN-1 and XY-WPDT
Following on from the article last month on USB-PD charging modules,
we shall now examine some of the many low-cost PD trigger/decoy and
tester modules that have appeared recently. These allow you to take
full advantage of the USB-PD chargers’ capabilities and use them as
versatile and efficient power supplies.
A
PD trigger is an interface
circuit that can manage the
negotiating protocols necessary
to request the required voltage and
current levels from a USB-PD supply,
as described last month. As soon as it
is connected to a USB-PD compatible
host, it engages with the host via the
CC1 or CC2 channels to achieve the
voltage and current levels that are
needed – assuming these are available.
Some of these modules are also
known as ‘decoy’ or ‘poll detectors’.
These terms all seem to mean much
the same thing as PD trigger.
Another variant combines the functions of a trigger/decoy module with
those of a USB-PD digital meter, so it
can display the available or selected
voltage(s) and current(s).
We’ll start by looking at the smallest, simplest and cheapest of the trigger modules.
ZY12PDN-3 ‘naked’ PD trigger
The ZY12PDN-3 module is tiny – see
the photos. Everything is mounted on
a PCB measuring just 30 x 15mm, with
the USB-C input socket at one end and
a small two-way screw terminal block
at the other end as the power output.
The ZY12PDN trigger module is
available in three versions, which differ only in their output connector or
lack thereof. Instead of the screw terminal block of the ZY12PDN-3, the
ZY12PDN-2 has a USB Type-A socket,
while the ZY12PDN-1 has no output
connector at all.
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The trigger circuitry on the PCB uses
two main chips: an STM32F030F4P6
microcontroller and a PBAFH device,
which is likely the USB physical
layer interface.
There’s also a small pushbutton
switch that can be used to select the
voltage and power level required
from the USB-C PD host, and an RGB
LED to indicate the selected voltage/
power level.
When the ZY12PDN is first connected to the PD host, the LED glows
red to indicate the default 5V supply
voltage. If you then press the button,
it will attempt to select a 9V supply.
If the PD host has this voltage available, it will switch its output to 9V, and
the LED will change to yellow. If you
press the pushbutton again, this will
The ZY12PDN-3
PD trigger,
shown enlarged
for clarity. There
are two other
versions of this
module with
either a USB
Type-A socket
or no connector
fitted instead
of the screw
terminal block.
attempt to change the supply voltage
to 12V. If the PD host has this voltage
available, it will switch its output to
12V, and the LED will change to green.
Further button presses will change the
voltage to 15V (light blue), then 20V
(dark blue) – again, assuming the host
can supply these voltages.
If the host doesn’t have one of the
voltages that is requested, then the
LED will glow purple, and the voltage
will stay at the highest voltage which
is available.
There’s also a ‘demo’ mode, where
the LED glows white and the supply
voltage cycles through the available
levels at approximately 1Hz.
If you plug the ZY12PDN into a host
port that does not support USB-PD
voltage and power negotiation, after
Reproduced by arrangement with
SILICON CHIP magazine 2022.
www.siliconchip.com.au
Practical Electronics | September | 2022
The WITRN
UPD005 is an
alternative to the
ZY12PDN module.
about four seconds, the LED will
flash blue to warn you that there
is no USB-PD support. However, it
will still pass through the normal 5V
VBUS power.
So, the ZY12PDN trigger module
essentially provides the ability to manually select the voltage from a USB-PD
power source. And it does this for a
cost of around £5-£8, depending on
how many you order and from which
Internet supplier.
It’s a bit limited in terms of the voltages you can request and has no provision for taking advantage of PPS ‘fine
tuning’, but if you just need the ability
to manually select one of the main PD
voltage levels, it is a good choice. For
example, you could use it in combination with a computer or USB charger
as a very basic bench supply to power
something like a breadboard.
There are other ‘naked’ trigger modules available that are very similar to
the ZY12PDN. One example is the
WITRN UPD005 V20, available from
suppliers like Banggood for much the
same price as the ZY12PDN. I obtained
one of these and tried it out, and it did
the job just as well as the ZY12PDN.
FNC88 PD trigger module
and meter
The FNC88 PD trigger is slightly larger
than the ZY12PDN, but not by much,
especially considering that it also
includes a digital meter. It measures
just 40 x 25 x 10mm, not including
the USB-C input plug. And it’s not
exactly ‘naked’ either, with a shield
PCB mounted 3mm below the main
PCB and a protective plastic sheet
above the 24mm diagonal colour
LCD screen.
It’s made by FNIRSI Technology
in Shenzhen, China, and is available
from quite a few internet suppliers,
including Banggood, for around £20
plus delivery.
It comes in a protective case with
a clear window, measuring 90 x 62
x 18mm. This should make it sturdy
enough for portable use.
The FNC88 PD unit has USB-PD
bidirectional capability, and this also
applies to the built-in digital meter.
So PD triggering and measurements
can be made using either the USB-C
plug at one end or the USB-C socket
at the other end as the power source,
with the opposite end connected to
the ‘sink’ device.
This also means that the FNC88 can
be connected between a USB-C cable
and the USB-C connector of either a
host or sink device.
On one side of the FNC88’s main
PCB, there’s a mini USB-C socket,
which extends its capabilities to measuring the current drawn by devices
with that type of USB connector. Then
on the other (‘top’) side are three tiny
pushbutton switches, and an equally
small slider switch.
The slider switch is to enable or
disable the trigger’s USB-PD protocol communicating ability, while the
three pushbuttons are used to select
the functions of the digital meter.
The specified supply voltage range
of the FNC88 is 4-24V, and its current
range extends from 0 to 5A, so it’s capable of dealing with all devices conforming to the current USB-PD specification.
The voltage measurement resolution
and accuracy are specified as 0.1mV
and ±(0.5% + 2LSD), while the current
measurement resolution and accuracy
are specified as 0.1mA and ±(1% +
2LSD). Quite impressive!
Other features of the FNC88 include
measurement and display of:
The power being drawn by the sink
device (0-150W, with a resolution
of 10mW).
The charge delivered to a battery over a known charging time
(0-99,999.9mAh with a resolution
of 0.1mAh).
The energy delivered to a battery
or other sink device over a known
delivery time (0-9999.999Wh with
a resolution of 1mWh).
The ability to record measurements
over a period of 0-999 hours, 59 minutes and 59 seconds with a resolution of one second and an accuracy
of 10 seconds/hour.
The PD trigger section of the FNC88
supports these protocols: QC2.0,
QC3.0, FCP, SCP, AFC and PD 3.0.
Although the FNC88 does not come
with any user operating manual, you
can download one as a PDF file from
the FNIRSI website at: https://bit.ly/
pe-sep22-fnc99
I gave the FNC88 a quick rundown,
comparing its voltage and current
readings with those from my Agilent U1251B DMM. This showed that
the accuracy and resolution of the
FNC88’s digital meter were within
their claimed figures.
So overall, the FNC88 seems to be
a very capable and useful device. My
only real complaint is that you need
either good eyesight or a strong magnifying glass to read the display on its
24mm diagonal LCD screen.
There are several other USB-C PD
trigger/DM devices available from
Banggood and other internet vendors. A good example is the Riden
TC66, which is almost precisely the
same size as the FNC88 and very similar in its functions and facilities. It’s
available for much the same cost as
the FNC88.
The front and rear view of the FNC88 module; you can just see the three function buttons at the bottom of the rear view,
along with the switch that connects the built-in PD chip to the CC1 pin.
Practical Electronics | September | 2022
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This side of the FNC88 module has a micro USB interface which is only used to
flash the firmware.
I have seen a suggestion on the
internet that the FNC88 might be a
knock-off of the TC66, or vice versa.
See: https://bit.ly/pe-sep22-tc66
XY-WPDT trigger unit and meter
Another USB-PD trigger/meter unit
available from many internet suppliers, including Banggood, is the
XY-WPDT. At the time of writing,
Banggood was selling it as a kit for
only £7.50 including delivery. It is
made by the same firm in China which
makes the XY-PDS100 ‘quick charger’
we looked at last month.
Although the XY-WPDT comes as a
kit, assembling it is not difficult and
doesn’t involve any soldering – just
the use of a very small Philips-head
screwdriver, which is included in the
kit. The PCB itself is already assembled, so all that remains is fitting the
front and rear panels around it using
the M2.5 screws and tapped spacers
provided.
When you complete the assembly,
the XY-WPDT measures a modest 61 x
25 x 11mm (not including the USB-C
plug protruding from its input end).
It’s only a little larger than the FNC88.
The main output is via a USB
Type-A socket at the opposite end
of the unit to the USB-C input plug,
and the XY-WPDT comes with a
100mm-long output cable with a
Type-A plug at one end and a 2.5mm
inner diameter concentric power connector at the other.
There are also a couple of USB-C
sockets on the unit itself near the
USB-C input plug, one on each side,
arranged so that the XY-WPDT can
measure the voltage and current passing between them.
The specifications of the XY-WPDT
are not all that different from that of
the FNC88. It can negotiate an output voltage between 4V and 20V
using either PD 2.0 or PD 3.0 protocols. It can adjust the voltage in
either 1V, 100mV or 20mV increments or decrements if the PD host
can respond to PPS negotiation (like
the XY-PDS100).
The meter function can measure
the voltage with a rated resolution
of 10mV and a precision of 0.3%,
and current with a rated resolution
of 1mA and a precision of 0.5%. Not
quite as good as the FNC88, but still
very useful.
The readout of the XY-WPDT is a
4-digit 7-segment LED display with
9mm-high digits, so although it is not
as fancy as that of the FNC88, it’s significantly easier to read.
Function switching is done via two
tiny pushbutton switches (K1 and K2),
one on either side of the unit. There
are also four indicator LEDs; three
indicate the voltage steps in PPS mode
(1V/100mV/20mV), with the remaining one indicating current measurement mode.
Like the FNC88, the XY-WPDT does
not come with any operating manual,
nor could I find a manual on the internet. The only information on using
it seemed to be in the XY-WPDT follow-up info on the Banggood website,
which turned out to be rather terse and
not easy to follow.
I gave the XY-WPDT a quick checkout coupled to the XY-PDS100 PD
charger, and the results were very
close to the rated figures for resolution and precision of both voltage
and current.
Overall then, the XY-WPDT PD trigger/meter is quite a good performer,
and very good value for money. My
only real complaint is that the method
it uses to select the voltage mode using
the two tiny pushbuttons K1 and K2
is really tricky, with various short and
long presses on each button making it
not at all easy to set the XY-WPDT to
a particular voltage level, especially
in PPS mode.
This seems to be because both buttons have different functions according to how long they’re pressed, so you
can easily flip things into a different
mode without meaning to.
In theory, the combination of the
XY-WPDT and the XY-PDS100 should
make a digitally adjustable DC power
supply with its output variable to any
voltage between 4V and 20V, but this
isn’t all that easy in practice.
It would be a lot easier if the two
tiny pushbuttons were increased in
The XY-WPDT is sold as a kit by Banggood, and only requires fitting the
components together with a screwdriver to assemble it; no soldering is necessary.
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Practical Electronics | September | 2022
number, with a smaller number of
functions per individual button and
less dependence on the time they
are pressed.
But for applications where you
want to ‘set and forget’, it works
acceptably well and provides excellent value for money.
Useful links
USB-C https://w.wiki/nto
USB-PD https://w.wiki/34dT
https://bit.ly/pe-sep22-usbc1
Quick Charge https://w.wiki/34dU
www.poscope.com/epe
The XY-PDS100 quick charger (detailed last month) is shown
connected to the XY-WPDT trigger unit, displaying the output voltage.
- USB
- Ethernet
- Web server
- Modbus
- CNC (Mach3/4)
- IO
- PWM
- Encoders
- LCD
- Analog inputs
- Compact PLC
- up to 256
- up to 32
microsteps
microsteps
- 50 V / 6 A
- 30 V / 2.5 A
- USB configuration
- Isolated
Here’s what the assembled XY-WPDT module looks like. The two extra USB-C
sockets on either side allow the unit to operate in pass-through mode.
PoScope Mega1+
PoScope Mega50
From left-to-right we have the USB-C input, PPS mode LEDs (1V, 100mV and
20mV steps), K1 switch, and current indicator LED. The USB-C input is used
with the matching output connector on the opposite side to control and measure
voltage or current. Pressing the K1 switch changes between displaying current
or voltage, while holding K1 just turns the screen and indicator LED off. Switch
K2 is used in conjunction with K1 to change the voltage setting, and is a bit more
complicated to set, see: https://bit.ly/pe-sep22-xy
- up to 50MS/s
- resolution up to 12bit
- Lowest power consumption
- Smallest and lightest
- 7 in 1: Oscilloscope, FFT, X/Y,
Recorder, Logic Analyzer, Protocol
decoder, Signal generator
Practical Electronics | September | 2022
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