System overview

UM1548

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Doc ID 023257 Rev 1

2.1.2

Modifying the RC5 device address and instructions for the three keys

The RC5.h file in the project folder (refer to the firmware for the AN2957 application note)

contains all the definitions for the standard device addresses as well as the device

instructions as per RC5 protocol. The global variables ‘Address’ and ‘Instruction’ defined in

main.c are used to store the RC5 address and instruction codes to be transmitted. In this

modified code, the MCU wakes up from Halt mode using external interrupt whenever any

key is pressed on the remote. The program then checks which particular key was pressed

and assigns the relevant RC5 address and instruction to the ‘Address’ and ‘Instruction’

variables respectively. It then calls the SendFrame() function to transmit the RC5 frame. This

process is repeated as long as the key is pressed. Once the key is released, the system

goes back to the low power Halt mode. The values that are assigned to the ‘Address’ and

‘Instruction’ variables can be changed inside the while(1) infinite loop in main.c file for each

of the three keys to customize the remote. This enables the remote to transmit any valid

RC5 frame for the three available keys.

2.2

Hardware layout

The STEVAL-IHM037V1 component layout for top and bottom layers is shown below in

Figure 5 and 6 respectively. It helps the user to locate different components/sections on the

board.

Figure 3.

Hardware layout: main board - top side