cmx918

DRM1000 module based on the CMX918 DRM tuner

"Covers broadcast bands from 530 kHz to 108 MHz."

Module datasheet

DRM1000 teardown:

See other photos in the IMAGES folder.

Chips:

• U1: CMX918 (CMX918Q5) - DRM tuner (no datasheet available) Structure diagram:

• U2: CMX655D - Audio codec Info

• U3: HX6537-A - Mircocontroller Datasheet

• U4: ?

• U5: ?

Test points, top:

• TP20 - ?
• TP2? - ?

Test points, bottom:

• TP1 - internal I2C SCK
• TP4 - internal I2C DATA

I2C addresses: CMX918 - 0x55, CMX655D - 0x57

• TP2 - ?

Digital data from the CMX918:

• TP9 - bit clock (15360 kHz in FM, 7680 kHz in VHF DRM, 768 kHz in AM and HF DRM) - connected to pin 41 of the microcontroller, PSPI_SCLK
• TP10 - sample clock (480 kHz in FM, 240 kHz in VHF DRM, 24 kHz in AM and HF DRM) - connected to pin 38 of the microcontroller, PSPI_CS0
• TP11 - data (32 bits per sample) - connected to pin 39 of the microcontroller, PSPI_SDIO0

Bit clock and sample clock at 24 kHz sample rate:

There are non-populated resistors on the module, which connect pins 27, 29, 28 to TP9, TP10, TP11.

• TP12 - ?
• TP16 - ?

I2S to the codec chip:

• TP22 - bit clock (2048 kHz in FM and VHF DRM, 1024 kHz in AM and HF DRM)

• TP28 - data (64 bits per sample)

• TP29 - L/R clock (32 kHz in FM and VHF DRM, 16 kHz in AM and HF DRM)

• TP24 - ?

• TP25 - ?

• TP26 - ?

• TP27 - ?

• TP30 - ?

Registers of the CMX918

• 0xD1, 0xD0 - status, RSSI ? - read every second

My prototype board

Do not want to buy a "CML Micro DE9180-2 Demo & Prototyping Kit for the DRM1000"? Make it yourself for $10.

Now I have access to the internal I2C as well as to the digital data from the CMX918.