# How to send AT commands on MangOH yellow board? **URL:** \ **Category:** mangOH Yellow\ **Created:** [July 21, 2020, 1:56am UTC](https://mangoh.discourse.group/t/how-to-send-at-commands-on-mangoh-yellow-board/4888 "2020-07-21T01:56:18Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![gisellefreude](https://avatars.discourse-cdn.com/v4/letter/g/a88e4f/32.png) [@gisellefreude](https://mangoh.discourse.group/u/gisellefreude)\ **Post date:** [July 21, 2020, 1:56am UTC](https://mangoh.discourse.group/t/how-to-send-at-commands-on-mangoh-yellow-board/4888/1 "2020-07-21T01:56:18Z")
Hi I just got my board and it looks good but none of the documents available have provided any information about how to connect the cellular chips UART (Rx and Tx). For my application, I can’t just use a USB connection. That makes no sense. And honestly would rather not have all the bells and whistles. Basically I just need to know how to send AT commands directly to the cellular chip and not have to go through linux or any bothersome USB port. Is this just the wrong board for me? I really like the chip but can’t find any options online for how to get the chip without it being surface mount. I need it to be prototyping friendly which is why I bought the MangOH yellow, but I’m frustrated because it seems a little too beginner friendly. So I guess what I want to know is if I can send AT commands WITHOUT using the usb port and if not, how can I get this cellular chip in a prototyping friendly format? ---
**Author:** ![jyijyi](https://sea2.discourse-cdn.com/flex016/user_avatar/mangoh.discourse.group/jyijyi/32/997_2.png) [@jyijyi](https://mangoh.discourse.group/u/jyijyi)\ **Post date:** [July 21, 2020, 2:04am UTC](https://mangoh.discourse.group/t/how-to-send-at-commands-on-mangoh-yellow-board/4888/2 "2020-07-21T02:04:08Z")
I believe there is a USB to UART connector to connect to the UART console. You can type “microcom /dev/ttyAT” there to enter AT command in the application. To quit the application, you can type ctrl+x. ---
**Author:** ![gisellefreude](https://avatars.discourse-cdn.com/v4/letter/g/a88e4f/32.png) [@gisellefreude](https://mangoh.discourse.group/u/gisellefreude)\ **Post date:** [July 21, 2020, 2:24am UTC](https://mangoh.discourse.group/t/how-to-send-at-commands-on-mangoh-yellow-board/4888/3 "2020-07-21T02:24:27Z")
Hi there thanks for responding. What i mean is, are there pins to connect to the uart? Normally on cellular modules there are Rx and Tx pins you can wire up to a microcontroller. For my application i can’t use a USB cable since i need my microcontroller to send the commands. As for the interface i would much rather use putty. Let me know if i should clarify anything. Giselle ---
**Author:** ![jyijyi](https://sea2.discourse-cdn.com/flex016/user_avatar/mangoh.discourse.group/jyijyi/32/997_2.png) [@jyijyi](https://mangoh.discourse.group/u/jyijyi)\ **Post date:** [July 21, 2020, 3:17am UTC](https://mangoh.discourse.group/t/how-to-send-at-commands-on-mangoh-yellow-board/4888/4 "2020-07-21T03:17:09Z")
suggest you taking a look on this schematic and see if there is testing point for you to use: > **[mangoh\_yellow\_21.pdf](https://mangoh.io/uploaded-documents/Reference/mangOH%20Yellow/Hardware/Schematics/mangoh_yellow_21.pdf)** > > 4.21 MB ---
**Author:** ![pinst](https://avatars.discourse-cdn.com/v4/letter/p/d78d45/32.png) [@pinst](https://mangoh.discourse.group/u/pinst)\ **Post date:** [July 21, 2020, 1:53pm UTC](https://mangoh.discourse.group/t/how-to-send-at-commands-on-mangoh-yellow-board/4888/5 "2020-07-21T13:53:11Z")
You can connect to UART1 through the expansion cable, we are doing that. You can also configure this port for AT commands with the AT!MAPUART command as described on page 80 of the AT command reference. However you are still going through the Linux processor. You cannot connect to the cell modem directly. If don’t want to use the Linux processor why not buy a product that doesn’t have one. ---
**Author:** ![gisellefreude](https://avatars.discourse-cdn.com/v4/letter/g/a88e4f/32.png) [@gisellefreude](https://mangoh.discourse.group/u/gisellefreude)\ **Post date:** [July 21, 2020, 6:18pm UTC](https://mangoh.discourse.group/t/how-to-send-at-commands-on-mangoh-yellow-board/4888/6 "2020-07-21T18:18:46Z")
This is helpful, thank you. I was wondering, is expansion cable the same thing as the expansion port? I noticed the mango yellow has a port with a bunch of pins on it where it looks like you could connect something. The schematic called it the expansion port. ---
**Author:** ![pinst](https://avatars.discourse-cdn.com/v4/letter/p/d78d45/32.png) [@pinst](https://mangoh.discourse.group/u/pinst)\ **Post date:** [July 22, 2020, 1:43pm UTC](https://mangoh.discourse.group/t/how-to-send-at-commands-on-mangoh-yellow-board/4888/7 "2020-07-22T13:43:01Z")
I think you mean the expansion connector as described on page 32 of the M-Y Hardware Architecture Guide. The expansion cable is the cable that plugs into the expansion connector. 😉 ---
**Author:** ![gisellefreude](https://avatars.discourse-cdn.com/v4/letter/g/a88e4f/32.png) [@gisellefreude](https://mangoh.discourse.group/u/gisellefreude)\ **Post date:** [July 22, 2020, 6:39pm UTC](https://mangoh.discourse.group/t/how-to-send-at-commands-on-mangoh-yellow-board/4888/8 "2020-07-22T18:39:54Z")
Oh goody! Thanks for pointing me there. I saw on page 28 of the architecture guide that they have a table saying what each pin on the expansion cable does! This is exactly what I was looking for. Thanks to everyone who kindly responded!