Aug 7, 2018
Test Equipment You Can Build
...
~ A Tale of Three
Platforms ~
"It was the best of times, it was the
worst of times" ...
The Arduino Nano, Teensy and ESP32 each contend for honors as
the the microcontroller on our Test Gadget motherboard!
Welcome!
Since last
episode, three controllers have evolved in consideration of being THE
controller on our Test Gadget motherboard ... the Arduino Nano, the
Teensy, and the ESP32. Each has strengths and weaknesses, but why not
continue to evolve our "GadgetRack" software to be used on each of those
three platforms?! After all, software for each is developed in the
standard Arduino IDE (integrated development environment) and common
libraries can be shared in each sketch.
We have been experimenting along these lines with each platform over the
past month and we explore this very opportunity (or dilemma) in
our CWTD program this time.
Do you want to have a cheap, small, dedicated Gadget? Or would you like
to have an all-inclusive Test Gadget "measurement station" on the
bench? Or perhaps you'd like to have a network-connected Gadget using
WiFi? Well, maybe you can have your cake and eat it too, as discussed
and illustrated this month!
Hope to see you on Teamspeak with us at 8pm ET Tuesday. Access details
(and all our previous episode whiteboards & podcasts!) are on the CWTD
home page ...
www.cwtd.org
73, George N2APB, Joe N2CX, Dave AD7JT
and DuWayne KV4QB
Podcast
Live Chat during
Show ...
<20:16:15> "George N2APB": A "grid" of various test functions we
envision for the Test Measurement Station was shown at the top of
our initial episode for this series of shows ... http://www.cwtd.org/2018-02-13.html
<21:11:13> "Terry N4TLF": Look at "Random Nerd Tutorials" for ESP32
tutroals as well
<21:20:52> "Leon - WØCOE": Thanks guys! I'm not usually around on
Tuesday nights, so it was fun to listen live for a change.
<21:21:09> "Terry N4TLF": thanks guys!
<21:21:32> "Gary vk2kyp": Thank you great show
CWTD Episode
#89:
A Tale
of Three Platforms: Nano, Teensy, ESP32
PLATFORM #1:
Arduino Nano
Here is the platform for our Test Gadgets thus far: an Arduino
Nano for low-cost computing power in an easy-to-use development
environment, a 16x2 serial character LCD for display, and a rotary
encoder for control, all on a Test Gadget motherboard. We the add
on specific-function Test Gadgets via smaller daughtercards that plug
into either side of the motherboard, thus enabling our little fixture to
serve (so far) as a signal generator, RF voltmeter and a DC ammeter ...
and later as a Scalar Network Analyzer, frequency counter, and more.
Resources:
1) LCD, blue, I2C serial, 16x2
char:
https://www.ebay.com/itm/1602-16x2-LCD-Character-Display-IIC-I2C-TWI-SPI-Serial-Interface-Board-Module-/262334510397?hash=item3d145af53d
http://www.mpja.com/mobile/Serial-2-X-16-LCD-Display-for-Arduino/productinfo/31164+MP/
2) Paxcoo Prototyping Boards ...https://www.amazon.com/gp/product/B01M7R5YIB/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
3) Arduino Nano Mini ...
https://www.ebay.com/itm/Arduino-board-Micro-controller-V3-0-ATmega328P-CH340G-5V-16M-Gift-USB-Nano-MINI/331853764136?_trkparms=aid%3D222007%26algo%3DSIM.MBE%26ao%3D1%26asc%3D20160908110712%26meid%3Dcab8be711bfb4b628ebb2c5ee08f606c%26pid%3D100677%26rk%3D1%26rkt%3D28%26sd%3D253099138551%26itm%3D331853764136&_trksid=p2385738.c100677.m4598
4) Solarbotics Power Regulator ...
https://solarbotics.com/product/34020/
PLATFORM #2: TEENSY
3.2 ... by Dave AD7JT
While N2APB and N2CX were continuing on with the Nano-based Test Gadget,
we decided to explore a little out in advance for a more powerful
controller to handle the increased performance needs of sweeping
frequencies and even a transceiver capability, yet still retaining the
comfortable Arduino IDE development environment. A number of
others in our homebrewing field were starting to take advantage of the
Teensy family of controllers, so with many more MIPs and I/O pins
available I took the plunge with the Teensy 3.2 platform.
The board
on the left is a Teensy 3.2 (https://www.pjrc.com/teensy/).
The link takes you to a page that describes the different versions of
the Teensy available and directs you to the Arduino odd-ons/plug-ins
needed to use the Arduino IDE. The instructions are pretty good and the
whole process went pretty smoothly. The little blue breakout board is
the Si5351 3-output DDS (
https://www.adafruit.com/product/2045 ). The clever copper-clad
cabinet holds a rotary encoder and the .98-inch display module. The
discrete components on the breadboard are the simple RF meter.
Here's the GadgetRack2 sketch running this Si5351 breakout board ...
GadgetRack2.zip
Teensy Resources:
PLATFORM #3:
ESP32 ... DuWayne, KV4QB
I designed a simple board to provide two pairs of headers so I
could plug in two 4x6 or 5x7 cm. modules at a time, or allow the use of a
single 8x12 cm. module. To keep the size down I have the ESP32 module
mounted on the back of the board along with a 5 V regulator to bring the 12
V supply I plan on using down to 5 V to power the ESP32 board. This
allowed me to keep the board size down to the 10x10 cm. size that qualifies
for the inexpensive rate from multiple Chinese board houses.
I found an ESP32 from www.EzSBC.com
that appears to have just about any IO type you could need.
Here is a list of what is available on the module. Of course
many of the pins are multipurpose so all of these functions are not
available at the same time. The module can be programmed directly from the
Arduino environment without pushing any buttons. The upload speed is 921600
bps, which makes program upload very fast.
·
240 MHz dual core Tensilica LX6 microcontroller with 600 DMIPS
·
Integrated 802.11BGN HT40 Wi-Fi transceiver, baseband, stack and
LWIP
·
Integrated dual mode Bluetooth (classic and BLE)
·
4 MByte flash
·
3 x UARTs, including hardware flow control
·
3 x SPI
·
2 x I2S
·
12 x ADC input channels
·
2 x DAC
·
2 x I2C
·
PWM/timer input/output available on every GPIO pin
·
SDIO master/slave 50 MHz
·
SD-card interface support
What I
liked about this version is that all the IO pins are brought out to single
row headers on each side of the module, that is only slightly larger than a
Nano. That and the fact that they are under $10, made this something I
wanted to try.
This Test Gadget a Signal Generator based on the
SI5351 clock generator. I had purchased a couple Chinese versions of the
Adafruit 5351 module when I was working on the 'Sweeperino Jr. ' and wanted
to see how well they worked.
This time I decided to mount the board vertical and
only use half of the connections. Since the module only uses power and the
I2C bus this made construction very easy. And, only using one set of
connector pins makes connecting the board much easier. And also left plenty
of room to mount an AD8307 log detector, so I can later use it as a SNA or
Wattmeter.
For the software I decided to use some in-line code
instead of one of the libraries that are available. I grabbed the SI5351
code from the uBITX by Jerry , KE7ER , and only had to make a couple minor
changes to get it to work as a 3 channel signal generator. This was just
removing a couple things that are specific to the uBITX. This code limits
the frequency range from .5 to just over 100 MHz., but that covers
everything I am interested in. The range can be lowered by a changing a
value if desired, but you will have to change that value back to get the
higher range again.
The use of a Joystick makes frequency selection very
easy. A horizontal movement changes the increment, while a vertical
movement increments or decrements the frequency. A test of the increment
value being changed, sets the color/background of the frequency display for
that column. This makes frequency changes very fast. A short press on the
Joystick button toggles through the three channels and a long press brings
you back to the main menu. The code is mainly contained in a while loop ,
with a couple support functions to display the frequency, or display
frequency being edited.
Here is a text file showing the functional part of
the sketch
(software). And here's the whole sketch:
ESP32TG1.zip.
See my blogspot covering this and all the previous
blog entries for the ESP32 test Gadget ...
http://kv4qb.blogspot.com/
And BTW, here's N2APB's ESP32 platform connected to
(and running) a crude version of Siggen for the DDS-60 card ...
