UART connection between HL7800 and MCU host


Currently there is a project I am going to choose HL7800 as Cat M1 communication.
My question is that, I can see three wiring methods for the connection between HL7800 and a MCU host, 8-wire, 4-wire and 2 wire, according to irPrime_HL7800_and_HL7800_M_Product_Technical_Specification_Rev3_1. But I cannot find the detail descriptions about these different connections. Where can I find them?



Are you asking what the functional differences are between the additional lines?

If so then these are all standard lines the functionality are openly documented in places like Wikipedia. Few people go for the full 8 wire implementation (as it is a bit heavy and a lot of the functionality is never used) but the minimum that we recommend is to use the 4 wire implementation to ensure data integrity.




Well received and thanks.

But is there any official document to describe these differences? I want to make it confirmed by a spec or something like that.



No there is no ‘official’ description of the line functionality as we rely on the IEEE defined specification of the signal, after that the conditions under which specific lines change or are set are modified as per the AT commands which are stated in the AT command manual.




Well received with thanks.


Hi, mlw,
Just want to confirm that, all the hardware connection between MCU and HL7800 are usart_tx, rx, cts, rts, and that’s enough. Do not need other bus like IIC and USB and SPI, etc. All I need is just send 100 bytes to back end server once a day.