Sending ack in lora

Hey every one.
Im using sx128 lora chip.
I want to set ack code in my coding and i cant find the function in library?
any body have any experience??

Could you please share which library you may be using?
Is it a LoRa or LoRaWAN library for the SX1280?
An SX1280 hw driver library will not have ACK functions as ACK is a MAC layer communication.

Are you trying to connect an SX1280 to TTN?
Do you have a 2.4G gateway?
The availability of 2.4G gateways on the network is near nil.

well my project is very simple . I want to send a packet of data and receive ack that gateway has received the packet correctly and then send second part.
Im using LoRa.h and 433MHz frequency.
my question is about how should i active CRC and ACK function that my teacher told me?
Is there any specific function or code to di this?
I normally did this by some loops but my teacher didnt accept that.

What sx chip and library are you using?
“Sx128” is not a full chip name.
I had assumed you meant SX1280, which appears to be wrong.

This forum is for LoRaWAN on TTN - not a general LoRa forum, so is very much off topic for the entire site.

You may wish to read the LoRa.h file - if it’s the Sandeep Mistry Arduino library you should see the CRC library functions and you’ll see there are no ACK library functions which is presumably what your teacher wants you to code by yourself rather than getting us to do it.