Codec Services

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HID Codec "cdc:HID"[edit]

Command Header Description
0x00010042 GetData
0x00020042 Initialize
0x00030000 Finalize


The touchscreen is the SPI device number 3, so it uses the 0x10142XXX SPI registers. It is initialized by issuing the following SPI commands:

spi_select_reg(3, 0x67);
spi_offset_mask(3, 0x26, 0x80, 0x80);
spi_select_reg(3, 0x67);
spi_offset_mask(3, 0x24, 0, 0x80);
spi_select_reg(3, 0x67);
spi_offset_mask(3, 0x25, 0x10, 0x3C);

Once the touchscreen is initialized, you can start polling touch data:

u8 raw_touchdata[0x40];
spi_select_reg(3, 0x67);
spi_read_offset(3, 0x26); //The return value of this is checked against "& 2"
spi_select_reg(3, 0xFB);
spi_read_offset_array(3, 1, raw_touchdata, 0x34);

This is the format of the touchdata report:

Offset Width Description
0x00 2*5 Five Touchscreen X Coordinates (big-endian MSB,LSB each. 12 bits number)
0x0A 2*5 Five Touchscreen Y Coordinates (big-endian MSB,LSB each. 12 bits number)
0x20 ?? ??

When the touchscreen is not touched, all the coordinates report 0xFFFF, and since touch coordinates have only 12 bits, you can check if the touchscreen is pressed by checking the 4th bit of the MSB. For example: pendown = !(raw_touchdata[0] & BIT(4))

MIC Codec "cdc:MIC"[edit]

Command Header Description
0x00010040 SetGain
0x00020080 GetGain
0x00030040 SetPower
0x00040080 GetPower
0x00050042 SetIirFilterMic

CSN Codec "cdc:CSN"[edit]

Command Header Description
0x00010040 ?
0x00020040 ?
0x00030040 ?
0x00040080 ?
0x00050040 ?
0x00060080 ?
0x00070040 ?
0x00080080 ?
0x00090040 ?

DSP Codec "cdc:DSP"[edit]

Command Header Description
0x00010042 ?
0x00020042 ?
0x00030082 ?
0x00040042 ?
0x000500C2 ?
0x00060080 ?
0x00070040 ?
0x00080040 ?

Legacy Codec "cdc:LGY"[edit]

Command Header Description
0x00010040 Powers on microphone ADC and clears bank3:idx3, then clears bank0xFF:idx5
0x00020040 Sets unknown CONFIG11 CODEC bits, writes 0x40 to bank0x67:idx0x25
0x00030040 Modifies bit5 in bank0x65:idx0x33

CHK Codec "cdc:CHK"[edit]

Command Header Description
0x000100C0 ReadSPI
0x000300C2 WriteSPI