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  • Author Author: dougw
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Henrietta's Daughter - Smart Thermostat

dougw

Henrietta's Daughter

 

Background

Cypress Semiconductor expressed interest in converting the Smarter Life Challenge projects to use the new PSoC4 Prototyping Kit to showcase the rich capabilities of this much lower cost module. The Henrietta Project was designed to look good with the PSoC4 Pioneer Kit at its heart, but the PSoC4 Prototyping Kit would look disproportionate in the same picture frame. So, I decided to shrink the system while maintaining the same functionality and being fully backward compatible with the firmware. I also wanted to switch from wire-wrap connections to a printed circuit board.

This led to a new design called Henrietta's Daughter because it is an offspring of the Henrietta Project.



Henrietta's Daughter


Objectives

The primary motive for the project was to demonstrate that the new PSoC4 Prototyping Kit from Cypress Semiconductor is just as capable as the PSoC4 Pioneer Kit (used in the Henrietta Project) in interfacing to a wide variety of sensors and subsystems. It actually has more pins brought out to connectors.

A secondary objective was to create a fairly general purpose interface card that would allow other applications to be implemented without additional wiring.

 

Compatible Features

Henrietta's Daughter has basically all the same features as the Henrietta Project and it is fully backward compatible with Henrietta firmware:

  • 2 graphical liquid crystal displays 84 x 48 pixels each
  • LED backlights for the LCDs driven by PWM for intensity control
  • 1 PWM servo motor
  • 1 digital input for an audio threshold module
  • 1 Cadmium sulfide light sensor used to control backlight intensity
  • 1 LM35 analog temperature sensor used to control furnace and air conditioner
  • Touch pad local user interface
  • Door activation switch
  • 1 DHT11 humidity sensor connector
  • a 3 channel furnace interface
  • 1 GPS to acquire accurate real time clock data
  • 1 Bluetooth module for wireless remote monitoring and control

 

These features are described in additional detail in the original blogs, so you can check them out there if desired.

 

New Features

There are a few minor new features:

  • There is now a daylight savings switch.
  • There are now 3 buttons which may be used to set the time in GPS denied locations.
  • There is a connector for the programming module (which is snapped off the PSoC4 Prototyping Kit)
  • There is a switch to connect a serial port to the programming connector. This is needed because the same port is also used to communicate with the GPS.
  • Powered via a mini USB 5 volt connector

 

The PCB

The PCB is actually pretty general purpose and may be used for all kinds of different applications. It features:

  • 2 SPI connectors (normally used for LCDs)
  • 2 UARTs (one is switched to a third connector) (normally used for Bluetooth and GPS)
  • an analog light sensor
  • an analog temperature sensor
  • 3 user pushbutton switches plus a fourth pushbutton on the Prototyping Kit
  • a slide switch
  • 3 digital I/O connectors - one has 1 channel, one has 3 channels and one has 4 channels
  • 1 PWM connector for a servo motor
  • 1 one wire serial connector
  • 3 LEDs

The best part is if a new application requires LCDs, GPS, Bluetooth, touch pad or optically isolated triacs, there is no wiring to do it is just plug-and-play.

 

The Build

The PCB cost $2 each to fabricate (because I bought 10 of them in a batch). I had to buy a few new parts, but had quite a few spares left over from the Henrietta Project. In particular I bought a slightly different GPS, but the original firmware still worked perfectly. The build went very smoothly, everything worked properly on the first try with no errors on the PCB. This paves the way to use the remaining 9 PCBs in new projects.

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Click image to view update

Here is a new version packaged in a 3D printed plastic case:

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Click image to view video

Here is an update with PLA faceplate instead of acrylic:

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Conclusions

The PSoC4 Prototyping Kit is so similar to the Pioneer kit, they can run the same firmware, but the new kit has a significantly lower cost.

The android app and PC app still work the same as they did with the Henrietta Project although the graphics in the PC app still reflect the old picture frame design.

  I ran the new version of PSoC Creator, which is a significant upgrade, but had no problems upgrading and compiling my old firmware. This development system provides phenomenal productivity, automating almost all of the implementation complexity inherent in devices of this level of power and sophistication, allowing the user to simply focus on what features they want.

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