24. Infrared interface (IRTIM)

An infrared interface (IRTIM) for remote control is available on the device. It can be used with an infrared LED to perform remote control functions.

It uses internal connections with TIM16 as shown in Figure 290 .

To generate the infrared remote control signals, the IR interface must be enabled and TIM16 channel 1 (TIM16_OC1) must be properly configured to generate correct waveforms.

The infrared receiver can be implemented easily through a basic input capture mode.

Figure 290. IRTIM internal hardware connections with TIM16 and TIM17

Figure 290: IRTIM internal hardware connections with TIM16 and TIM17. The diagram shows two timer output channels, TIM17_CH1 and TIM16_CH1, connected to an IRTIM block. TIM17_CH1 is connected to the top input of an AND gate, and TIM16_CH1 is connected to the bottom input. The output of the AND gate is connected to the IR_OUT pin. Above TIM17_CH1 is a waveform showing a high-frequency carrier signal. Above TIM16_CH1 is a waveform showing a low-frequency modulation envelope. The output waveform on the IR_OUT pin shows the modulated carrier signal. The diagram is labeled MS34517V1 in the bottom right corner.

The diagram illustrates the internal hardware connections for the Infrared Interface (IRTIM). It features two timer output channels, TIM17_CH1 and TIM16_CH1, which are inputs to an IRTIM block containing an AND gate. TIM17_CH1 provides a high-frequency carrier signal, while TIM16_CH1 provides a low-frequency modulation envelope. The output of the AND gate is the IR_OUT pin, which produces a modulated carrier signal. Waveforms are shown for each input and the output to illustrate the signal types.

Figure 290: IRTIM internal hardware connections with TIM16 and TIM17. The diagram shows two timer output channels, TIM17_CH1 and TIM16_CH1, connected to an IRTIM block. TIM17_CH1 is connected to the top input of an AND gate, and TIM16_CH1 is connected to the bottom input. The output of the AND gate is connected to the IR_OUT pin. Above TIM17_CH1 is a waveform showing a high-frequency carrier signal. Above TIM16_CH1 is a waveform showing a low-frequency modulation envelope. The output waveform on the IR_OUT pin shows the modulated carrier signal. The diagram is labeled MS34517V1 in the bottom right corner.

All standard IR pulse modulation modes can be obtained by programming the two timer output compare channels.

TIM17 is used to generate the high frequency carrier signal, while TIM16 generates the modulation envelope.

The infrared function is output on the IR_OUT pin. The activation of this function is done through the GPIOx_AFRx register by enabling the related alternate function bit.

The high sink LED driver capability (only available on the PB9 pin) can be activated through the I2C_PB9_FMP bit in the SYSCFG_CFGR1 register and used to sink the high current needed to directly control an infrared LED.