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I am trying to use the the simcom AT command set to change the preferred band on my "SIM5216E" module. I know I need to use the AT+CNBP command, but I am unsure of what code I need to enter to select WCDMA 850 only.Screen shot of command manual

The above screen shot is of the command manual. The whole manual can be found here: "http://mt-system.ru/sites/default/files/documents/simcom_sim5215_sim5216_atc_en_v1.21.pdf" I am unsure of how the number system is supposed to work. If someone could provide me with the WCDMA 850 code it would be much appreciated.

Thank-you for your time.

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closed as off-topic by Chetan Bhargava, Matt Young, Joe Hass, Daniel Grillo, Keelan Apr 7 '14 at 8:36

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From the table WCDMA 850 is 26 so you need to shift 1 across 26 bits which in binary would be 100000000000000000000000000 which is 4000000 in the hexadecimal notation that command requires, so it should be:

AT+CNBP=0x0000000004000000

I've left the leading zeroes in place as shown in a datasheet example, I'm not sure if they'd be required or not. If you're a Windows user you can use the calculator to do the same conversion by selecting View | Programmer mode, entering 1 followed by a press of the "Lsh" (left-shift) button and then 26 followed by the "=" button. Then press the Hex button to get the result in hexadecimal.

As you've found that the module is not working with that bit set to work back from an example of the AT+CNBP? where you received the result 0x000700000FFF0380 if I paste that into the Windows calculator while Hex mode is selected and then press the Bin (Binary) button I get the following result:

111000000000000000000001111111111110000001110000000
                        ^ WCDMA_850

This result has 51 binary digits (numbering starts at zero) and reading from right (which is bit zero) to left (which is bit 50) you can see that WCDMA 850 is enabled. However that's not a guarantee that the module variant you have actually supports it and if it doesn't it may not like that bit being the only one selected. It may be worth trying to replace some of the selected bits to confirm it. For example if you know GSM 850 is currently being used perhaps try the following:

000000000000000000000000100000010000000000000000000
                        ^ WCDMA_850
                               ^ GSM_850

Which back in hex with the leading zeroes is 0x0000000004080000. If you're unsure which network is currently being used the AT+CPSI? command provides that.

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  • \$\begingroup\$ Hold on, the module actually didn't accept that code. I have tried the other two listed in the example and they seem to work fine. Any other thoughts? \$\endgroup\$ – Eddie1598 Apr 6 '14 at 3:53
  • \$\begingroup\$ I double-checked and the number conversion looks correct, I'm just taking another look at the datasheet to see if I can spot another reason, maybe it doesn't like some combinations of values. \$\endgroup\$ – PeterJ Apr 6 '14 at 4:06
  • \$\begingroup\$ The example in the datasheet doesn't set that particular bit, after powering back on the module what does the AT+CNBP? command display? I'm thinking either the variant of module you have may not support that mode, or that it only works with some other bits set. \$\endgroup\$ – PeterJ Apr 6 '14 at 4:14
  • \$\begingroup\$ So the module is on. I've entered "AT+CNBP=0x000700000FFF0380" and the response was "OK". I rebooted the module and entered "AT+CNBP?" as you requested and the response was "+CNBP: 0x000700000FFF0380 OK". I am not sure what that band would even be, but it works as a command. \$\endgroup\$ – Eddie1598 Apr 6 '14 at 4:29
  • \$\begingroup\$ I've included a few more details including how to calculate for multiple bits etc. I noticed the result has every bit from the table set, so as above if it doesn't support that mode it might not like it being the only one selected. See how you go and if you get any other answers, someone may come along that's familiar with that particular device. \$\endgroup\$ – PeterJ Apr 6 '14 at 5:08

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