Interfacing face recognizing module with PIC serial comm help

[Veketti]

Dear All,

I'm playing around with Hi-Link HLK-TX510 face recognizing module and trying to interface that with PIC 16F1847 micro. I've pretty much done the PIC program and decoded with scope that it sends the correct message. However I'm bit unsure with few things before I connect those two together and possibly fry the relatively expensive module, so I hope someone could be so kind and answer following guestions..

1. In this page https://blakadder.com/hlk-tx510/ it is said that the connection should be from the TX510 side SD0 -> RX and SCLK -> TX. However in the schematic they look to be I2C and not UART. Is there error or should it actually be pins 4 and 5 which are marked CK805_UART_RXD and CK805_UART_TXD? If the web page is correct and it is SD0 and SCLK then should it be USI1_SD0 and USI1_SCLK or USI0_x?
1. Should the serial communication be idle low, or idle high?
2. PIC serial communication is 5VDC. Is that ok with the receiving unit, or should it be 3.3V or something?

Documentation what available can be found from github: https://github.com/blakadder/HLK-TX510

Thank you in advance!

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edit July 26th.

I was able to get help from the manufacturer Hi-Link. I'll add it here if someone will be stumbling with the same thing.
1. Pins are from TX510 connector P2 as following: RX -> pin 6 USI1_SD0 and TX -> pin 7 USI1_SCLK
2. Idle HIGH
3. 5 VDC