UM1548
User manual
IR remote trasmitter STEVAL-IHM037V1
Introduction
The IR transmitter solution features three buttons which can be used to transmit three
unique IR commands for various IR remote control applications. It is a direct implementation
of the AN2957 application note, ‘Implementing an RC5 infrared transmitter using the IR
timer modulator of the STM8L101xx microcontroller’. An STM8L101xx low power MCU is
used to implement this design. The existing firmware, which is supplied with the application
note, was modified slightly to accommodate for the three keys present in the design which
are used to control speed-up, speed-down and power-on/off toggle operations. The circuit
runs on a CR2032 coin cell battery and is designed to fit into a small key fob type enclosure.
Figure 1.
IR remote transmitter STEVAL-IHM037V1
This document explains the different parts and functions of the IR remote transmitter.
December 2012
Doc ID 023257 Rev 1
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www.st.com
Contents
UM1548
Contents
1
Getting started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1
1.2
Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Initial setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2
System overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1
Hardware design description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1.1
2.1.2
STEVAL-IHM037V1 IR remote transmitter . . . . . . . . . . . . . . . . . . . . . . . 5
Modifying the RC5 device address and instructions for the three keys . . 6
2.2
Hardware layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3
Hardware schematics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.1
Bill of materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Appendix A Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
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UM1548
List of figures
List of figures
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
IR remote transmitter STEVAL-IHM037V1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
IR transmitter in key fob enclosure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Hardware layout: main board - top side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Hardware layout: main board - bottom side . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
IR remote transmitter STEVAL-IHM037V1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Remote fan speed controller. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
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Getting started
UM1548
1
1.1
Getting started
Package
The remote fan speed controller includes the following:
●
Hardware content:
–
IR transmitter board with key fob enclosure including three-button carbon contact
pad
User manual (this document)
Schematics, Gerber files, BOM
Already programmed STM8L device soldered on the demonstration board
Object files are also available for the firmware.
●
Documentation:
–
–
●
Firmware
–
–
1.2
Initial setup
The IR remote controller board can be set up as follows:
1.
2.
3.
Remove the board from the enclosure using a flat head screwdriver to separate the two
parts of the key fob enclosure.
Install a CR2032 battery by sliding it into the battery retainer on the bottom side of the
PCB with the battery +ve terminal on top, as indicated on the retainer.
Place the board back inside the upper half of the enclosure containing the slot for the
carbon contact pad such that the contact switch footprints on the top layer are aligned
below the carbon contact pad.
Snap fit the lower part of the enclosure by applying gentle pressure all around so that
the two pieces lock into each other.
Now the key fob can be used to transmit the pre-programmed IR RC5 commands used
to control the fan speed/dimmer intensity and it's ON/OFF state.
4.
5.
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UM1548
System overview
2
2.1
System overview
Hardware design description
Figure 2.
IR transmitter in key fob enclosure
Speed up
On/off
Speed
down
AM12361v1
2.1.1
STEVAL-IHM037V1 IR remote transmitter
This application is based on the direct implementation of the ST application note AN2957
with slight modifications to support the three keys.
Table 1
lists the commands used for the three keys on the transmitter:
Table 1.
RC5 commands
Device address
SAT1 [8]
SAT1 [8]
SAT1 [8]
Device instruction
Number 8 [8]
Number 0 [0]
Balance left [27]
14 bits transmitted
10X01000001000
10X01000000000
10X01000011011
Key function
Speed up
On/off
Speed down
The RC5 frame is 14 bits long and comprises the following:
●
●
●
●
●
1 start bit (always 1)
1 field bit
1 toggle bit (represented in
Table 1
as X). It changes state every time a key is released
and pressed again.
5-bit device address (32 possible addresses)
6-bit device instruction (64 possible instructions).
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