# Help me! Where can I find the bx3105 spi communication guide? **URL:** \ **Category:** IoT Modules\ **Created:** [March 18, 2019, 12:12am UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729 "2019-03-18T00:12:29Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![parkss093642](https://avatars.discourse-cdn.com/v4/letter/p/c77e96/32.png) [@parkss093642](https://forum.sierrawireless.com/u/parkss093642)\ **Post date:** [March 18, 2019, 12:12am UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/1 "2019-03-18T00:12:29Z")
I would like to control the mcu and bx3105 modules via spi communication, but the bx310x manual I found did not give clear instructions. Where can I check the communication protocols and clocks needed for spi communication? ---
**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:** [March 18, 2019, 1:17am UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/2 "2019-03-18T01:17:56Z")
see if this helps you: > [@BX100 AT Command for SPI Error](https://forum.sierrawireless.com/t/bx100-at-command-for-spi-error/15538/2): > > @dargaj, I am assuming you are talking about the BX3100? I suspect that your firmware is not 2.5+ ati BX310x OK at+cmgr BX310x.2.5.0-2 OK at OK at+srspi? +SRSPI: 0,0 OK at+srspi=1,1 OK Couple of other things as they are not well documented. SPI Frame: command 2 bytes payload\_length 2 bytes more 1 byte reserved 3 bytes payload 256 bytes \ 0x0001: AT command 0x0002: AT response 0x0003: data (data mode) 0xffff: dummy data \: Length of the significan… ---
**Author:** ![parkss093642](https://avatars.discourse-cdn.com/v4/letter/p/c77e96/32.png) [@parkss093642](https://forum.sierrawireless.com/u/parkss093642)\ **Post date:** [March 18, 2019, 6:49am UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/3 "2019-03-18T06:49:58Z")
Thank you very much.!!! But I have updated the firmware version. And I confirmed that the following text is printed. Sierra Wireless Copyright 2018 BX310x.2.5.0-2 READY If the above statement is output, dummy-slave-msg is not output, but after that, dummy-slave-msg is output again. So I think there is a problem with the data transmission, but I can not solve it. I created the data format below and sent it to for. And stored in an array to check the return value of all the data. typedef struct format { byte command [CMD\_MAX]; // command 2bytes byte payloadLength [LENGTH\_MAX]; // length 2 bytes byte more; // more byte reserved [RESERVED\_MAX]; // reserved byte payload [PAYLOAD\_MAX]; // payload 256bytes } spiFormalt; spiFormalt protocol = { {0x00, 0x01}, // command {0x00, 0x03}, // payload length 0x00, // more {0x00, 0x00, 0x00}, // reserved {0x41, 0x54, 0x0d,} // payload }; for (int i = 0; i \ **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:** [March 18, 2019, 7:07am UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/4 "2019-03-18T07:07:37Z") What is the value of CMD\_MAX, LENGTH\_MAX,PAYLOAD\_MAX? From your code, you seems only send the command… did you pull the GPIO17 to high? did you connect SPI chip-select of BX module? What do mean by DUMMY-SLAVE-MSG from the eighth element to the 22nd element? Is there is any output from BX module? ---
**Author:** ![Engineer](https://avatars.discourse-cdn.com/v4/letter/e/8baadc/32.png) [@Engineer](https://forum.sierrawireless.com/u/Engineer)\ **Post date:** [August 6, 2019, 2:06pm UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/5 "2019-08-06T14:06:11Z")
Hello. I have a problem getting an answer on spi. All my requests are answered “DUMMY-SLAVE-MSG”. How to send a command and receive a response in accordance with the Protocol ? If possible, demonstrate with an example. Thank you in advance for your help. ---
**Author:** ![jeffrey.harris](https://avatars.discourse-cdn.com/v4/letter/j/bcef8e/32.png) [@jeffrey.harris](https://forum.sierrawireless.com/u/jeffrey.harris)\ **Post date:** [October 1, 2019, 1:19pm UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/6 "2019-10-01T13:19:28Z")
Hello Engineer and jyijyi Has this problem a solution as we have exactly the same problem here. We get the Sierra wireless reply correctly but following that we get a DUMMY-SLAVE-MSG from the BX3105 but it does not start at the beginning of the frame but some time after e.g. 15 bytes of 0 followed by the start of the frame. Why do we not get the frame starting when the CS is selected and the clock starts? Thank you ---
**Author:** ![maizezoidberg](https://avatars.discourse-cdn.com/v4/letter/m/c0e974/32.png) [@maizezoidberg](https://forum.sierrawireless.com/u/maizezoidberg)\ **Post date:** [January 20, 2020, 5:29pm UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/7 "2020-01-20T17:29:57Z")
We have some problem too. Any commands have DUMMY-SLAVE-MSG answer. Did anybody solve it? ---
**Author:** ![alberthuang](https://avatars.discourse-cdn.com/v4/letter/a/53a042/32.png) [@alberthuang](https://forum.sierrawireless.com/u/alberthuang)\ **Post date:** [January 31, 2020, 3:12am UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/8 "2020-01-31T03:12:17Z")
I referenced this document ,but just display DUMMY-SLAVE-MSG too. How can I get correct status with AT command on SPI mode? [SPI](https://forum.sierrawireless.com/uploads/short-url/i2Labnh7zQ4z1iFZUKCQCyl4JNS.pdf) ---
**Author:** ![alberthuang](https://avatars.discourse-cdn.com/v4/letter/a/53a042/32.png) [@alberthuang](https://forum.sierrawireless.com/u/alberthuang)\ **Post date:** [February 6, 2020, 6:30am UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/9 "2020-02-06T06:30:10Z")
Hi maizezoidberg, I successful got correct response. If you still have same status, email to me. [ahwow120509@gmail.com](mailto:ahwow120509@gmail.com) ---
**Author:** ![paolo.ferretti](https://sea1.discourse-cdn.com/flex025/user_avatar/forum.sierrawireless.com/paolo.ferretti/32/5186_2.png) [@paolo.ferretti](https://forum.sierrawireless.com/u/paolo.ferretti)\ **Post date:** [May 5, 2020, 12:27pm UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/11 "2020-05-05T12:27:22Z")
Hello, I approach to use the BX3105 module with SPI communication. I was wondering if there is a detailed document were protocol commands and answers are described. If I have not misunderstood the AT commands are transposed on SPI. Is there a specification on this? Do you have any suggestions for me to avoid mistakes and waste of time? Is there some code sample? Thanks in advance ---
**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:** [May 5, 2020, 2:07pm UTC](https://forum.sierrawireless.com/t/help-me-where-can-i-find-the-bx3105-spi-communication-guide/15729/12 "2020-05-05T14:07:02Z")
Here has the protocol: > [@BX100 AT Command for SPI Error](https://forum.sierrawireless.com/t/bx100-at-command-for-spi-error/15538/2): > > @dargaj, I am assuming you are talking about the BX3100? I suspect that your firmware is not 2.5+ ati BX310x OK at+cmgr BX310x.2.5.0-2 OK at OK at+srspi? +SRSPI: 0,0 OK at+srspi=1,1 OK Couple of other things as they are not well documented. SPI Frame: command 2 bytes payload\_length 2 bytes more 1 byte reserved 3 bytes payload 256 bytes \ 0x0001: AT command 0x0002: AT response 0x0003: data (data mode) 0xffff: dummy data \: Length of the significan… I have tested both FW 2.6.3 and 2.7.2, it is working fine.