# Problem with AT Command **URL:** \ **Category:** RC76\ **Tags:** debug\ **Created:** [July 25, 2021, 6:42am UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371 "2021-07-25T06:42:23Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![toan\_tran123](https://avatars.discourse-cdn.com/v4/letter/t/c57346/32.png) [@toan\_tran123](https://forum.sierrawireless.com/u/toan_tran123)\ **Post date:** [July 25, 2021, 6:42am UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/1 "2021-07-25T06:42:23Z")
Hi, I am using module RC7620 in my product. The module we are designed to use with UART. The big problem is the AT command doesn’t work well: it is often stuck. We’re trying to debug this problem: - We are using MangOH yellow kit, connect UART pin of RC7620 with USB to COM. - We are making a phone call from RC7620 to Android phone, accept from Android then wait for the response from RC7620. - Use case 1: The kit using the external battery without connecting the USB port. After Android connects the call, RC7620 doesn’t respond anything. - Use case 2: After the module doesn’t respond, we are tried to connect USB port with external power (the module still working), the external battery still connects. We are tried to make a phone call again. When Android accepts the call, RC7620 responds normally. The battery is quite good, the stuck happens with many commands (this call command is an example), and this issue happens with lots of RC7620 we have. I don’t know does USB can affect the AT command. We debug this issue for a long time, many methods using but doesn’t work. The video is attached below: > **[3395064478.mp4 (video)](https://drive.google.com/file/d/1DTiAeME6ZBTMdoyUGFDsYVPB7YIQf_z_/view?usp=sharing)** > > Google Drive file. Please help me resolve this problem. Thank you very much. Toan ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [July 25, 2021, 12:30pm UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/2 "2021-07-25T12:30:09Z")
does AT command port stuck if setting AT+KSLEEP=0 but controlling the DTR to make module waking up? ---
**Author:** ![toan\_tran123](https://avatars.discourse-cdn.com/v4/letter/t/c57346/32.png) [@toan\_tran123](https://forum.sierrawireless.com/u/toan_tran123)\ **Post date:** [July 25, 2021, 1:41pm UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/3 "2021-07-25T13:41:39Z")
Hi @jyijyi , We are tried both AT+KSLEEP=0 with DTR, and AT+KSLEEP=2. Nothing works. Thanks, Toan ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [July 25, 2021, 2:18pm UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/4 "2021-07-25T14:18:50Z")
You mean it is still stuck? Or just the "connect " not returned? ---
**Author:** ![toan\_tran123](https://avatars.discourse-cdn.com/v4/letter/t/c57346/32.png) [@toan\_tran123](https://forum.sierrawireless.com/u/toan_tran123)\ **Post date:** [July 25, 2021, 2:21pm UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/5 "2021-07-25T14:21:33Z")
It’s both stuck and not repond URC code after connect ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [July 25, 2021, 2:22pm UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/6 "2021-07-25T14:22:05Z")
Is it duplicate issue? > [@UART AT Command hang when make a phone call](https://forum.sierrawireless.com/t/uart-at-command-hang-when-make-a-phone-call/24353/12): > > does problem happen if setting AT+KSLEEP=1 ? ---
**Author:** ![toan\_tran123](https://avatars.discourse-cdn.com/v4/letter/t/c57346/32.png) [@toan\_tran123](https://forum.sierrawireless.com/u/toan_tran123)\ **Post date:** [July 25, 2021, 2:23pm UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/7 "2021-07-25T14:23:17Z")
yes, you can reference my comment and video to help us fix this issue Thanks ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [July 25, 2021, 2:24pm UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/8 "2021-07-25T14:24:30Z")
Then you don’t need to open duplicate topic ---
**Author:** ![toan\_tran123](https://avatars.discourse-cdn.com/v4/letter/t/c57346/32.png) [@toan\_tran123](https://forum.sierrawireless.com/u/toan_tran123)\ **Post date:** [July 25, 2021, 2:26pm UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/9 "2021-07-25T14:26:55Z")
Thankyou, Now I will focus to the root topic. Thanks ---
**Author:** ![jyijyi](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/jyijyi/32/4766_2.png) [@jyijyi](https://forum.sierrawireless.com/u/jyijyi)\ **Post date:** [July 26, 2021, 1:51am UTC](https://forum.sierrawireless.com/t/problem-with-at-command/24371/10 "2021-07-26T01:51:18Z")
Yes, let’s go back to the original discussion thread then.