September 2012 Doc ID 023172 Rev 1 1/43
UM1542
User manual
Cold thermostat kit based on AC switches and the STM8S003F3
Introduction
The STEVAL-IHT001V2 thermostat kit (Figure 1) provides a robust and low-cost solution
from STMicroelectronics using a microcontroller and AC switches to control a refrigerator, a
freezer or a fridge/freezer combination. The firmware embeds three different thermostat
control versions: basic (just for compressor and light control), defrost (with defrost resistor
control added) and air circulation (with fan control added). This allows a wide section of the
cold appliances market to be addressed.
The STEVAL-IHT001V2 board controls a single-phase induction motor and a light bulb, and,
optionally, a defrost resistor and a fan, operating on 220/240 V RMS 50/60 Hz mains
voltage. The thermostat kit is operational with 100/120 V RMS 50/60 Hz but a supply
capacitor must be chosen for a 30 mA output DC current (see Appendix H).
The board can operate over an ambient temperature range of 0 to 60 °C. The exact
maximum temperature depends on the power of the loads (Section 3.2).
Figure 1. STEVAL-IHT001V2 board
For demonstration and application development purposes a graphical user interface (GUI)
has been developed. The PC and STM8 microcontroller, the MCU performing thermostat
regulation, are connected through a USB bus. Since the STM8 MCU is a low-cost MCU not
embedding a USB peripheral, a supplementary STM32 MCU has been added as a bridge
between the PC and STM8 MCU, only in order to allow communication through the GUI.
The GUI is not only used to configure the thermostat (basic, defrost, air circulation), but also
allows control parameters to be set and parameters measured during tests to be obtained
(Section 3.6). This document provides users with all the information needed to get started
with and operate the STEVAL-IHT001V2 thermostat kit. For detailed information on how to
access the MCU in order to modify/measure parameters, please refer to the “Help” menu of
the GUI software.
www.st.com
Contents UM1542
2/43 Doc ID 023172 Rev 1
Contents
1 Kit introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.1 Package contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 Board presentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1 Performance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 Ensured functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.1 Temperature control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.2 Compressor control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.3 Light bulb and buzzer control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.4 Defrost resistor and fan control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.3 Hardware features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.1 ACS and ACST devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.2 STM8S003 microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3.3 Control side and communication side power supplies . . . . . . . . . . . . . . 12
2.3.4 STM32F103 microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.4 Graphic user interface (GUI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3 Using the STEVAL-IHT001V2 thermostat kit . . . . . . . . . . . . . . . . . . . . . 14
3.1 Thermostat versions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.2 Loads power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
3.3 Measure points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.4 Pulse control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
3.5 Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.5.1 Jumper configuration for standalone or PC-driven modes . . . . . . . . . . . 17
3.5.2 Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.5.3 Operating modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
3.5.4 Instructions for the GUI software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.6 GUI windows description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.6.1 Temperature control tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
3.6.2 Timing control tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3.6.3 Force debug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3.6.4 Parameter measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
