Espressif ESP32 Technical Reference Manual page 323

12 I2S Controller (I2S)
As is shown in Figure 12-11, the I2S_RX_PDM_EN bit and the I2S_PDM2PCM_CONV_EN bit of register I2S_PDM_
CONF_REG should be set to 1, in order to use the PDM receiving module. As is shown in Figure 12-12, the
PDM receiving module will convert the received PDM signal into a 16-bit PCM signal. Filter group1 is used to
downsample the PDM signal, and the I2S_RX_PDM_SINC_DSR_16_EN bit of register I2S_PDM_CONF_REG is
used to adjust the corresponding down-sampling rate.
Table 12-7 shows the configuration of the I2S_RX_PDM_SINC_DSR_16_EN bit whose PCM signal frequency
remains 48 KHz at different PDM signal frequencies.
PDM freq (KHz)
×128
f
pcm
×64
f
pcm
12.5 Camera-LCD Controller
There are three operational modes in the LCD mode of ESP32 I2S:
• LCD master transmitting mode
• Camera slave receiving mode
• ADC/DAC mode
Espressif Systems
Figure 12-10. PDM Sends Signal
Figure 12-11. PDM Receives Signal
Figure 12-12. PDM Receive Module
Table 12-7. Down-sampling Configuration
I2S_RX_PDM_SINC_DSR_16_EN
1
0
323
Submit Documentation Feedback
PCM freq (KHz)
f
pcm
ESP32 TRM (Version 5.2)