FX3 TX de-emphasis value

[DaSe_3581511]

Hello,

inside the FX3 firmware the function CyU3PReturnStatus_t CyU3PUsbSetTxDeemphasis (uint32_t value) can be used to set the TX de-emphasis setting for the USB 3.0 signal. The Tx de-emphasis value should be less than 0x1F and default value is 0x11.

USB3 specifies TX de-emphasis from min 3.0 dB to max 4.0 dB (nominal is 3.5 dB).

What is the relation between the digital hex values and the values in dB?

Many thanks in advance

Daniel

[Rashi_Vatsa · Accepted solution]

Hello,

Please find the formula for calculating corresponding Tx de-emphasis (dB) value 

Tx de-emphasis (dB) = 20 *log₁₀  [(128 − 2 * tx_deemphasis value) /128]

Note:  tx_deemphasis value is the value set using CyU3PUsbSetTxDeemphasis API

[DaSe_3581511]

Thanks a lot for the fast response Rashi.

Regards,

Daniel