HL7800 no power to SIM

Having problems with an HL7800.
The module is not able to talk to the SIM.
No power seems to be getting to it from UIM1_VCC.
UIM1_DETECT is tied high via a 100k resistor. No difference if tied directly to 1.8V

I also get strange results when asking about the SIM

According to the AT reference, I should get either…

​or +CME ERROR: ​

But all I get is a single word ERROR

I also tried to manually feed the SIM card with 1.8V…….but nothing.

Any help would be appreciated.

Suggest check first with HL78 development kit.

Yes I agree. Which is what I did.
Things work normally in the kit As expected.

I went so far as to mimic the circuitry around the SIM that the kit has on our prototype. But no joy.

Then I suggest you contact with Sierra sales/technical support person,
and ask for a schematic review.
Or share your part of SIM circuit schematic here to see if somebody can help.

Okay. My support person is away, so I’ll attach my schematic.

Here’s a link to the HL7800 sheet

HL7800 Schematic

One thing not on this schematic is that I have tied the SIM detect high for testing. Though the documentation says it can be left floating.

Yes, I am having the same trouble, and before I read your post. No joy…

I cant see either the 1.8V rail for the sim coming up, or any activity on the serial clock lines.


If you tied UIM1_DET (pin 64) to 1.8V, then the SIM interface HW design is OK.

Not sure what is wrong with the design. Please contact technical support person for design review and sample evaluation.

I am having the same issue. But I have the UIM1_DET(pin 64) floating as it says in the datasheet.

I had it both floating and tied high as well, but it made no difference.

I had an SE take a look at it and he said he got my prototype to work but he had to change the SIM card holder. I’m expecting it back from him soon and will be able to share what his findings are.

You also need to be running the lates HL78 firmware which is in Beta.

-Henrique Reis

OmegaWorks Inc

Ok. I had the HL78 firmware that comes with the device. I would try to update to the latest beta and try again.
Could you please post where I can find the latest firmware for the hl78? I haven’t been able to…

Thanks !

BHL7800. (3 MB) BHL7800. (1.2 MB)

Please remove .z in the filename and unzip it.

I have updated the module to version you provided but I still have the same issue.
2019/05/31 22:53:05
Legato RTOS: 18.09.2.ALT1250.rc14 2019/05/28 19:45:55
atSwi: 16.00
UBOOT: 01.03
Apps: RKAPP_02_01_01_00_48__924f867b77e881511a058851877a5fdd71d8a107
PHY: 12.50.212633
PMP: 212636

ibs92, what SIM card holder are you using? what part number is it?

The only thing that my SE did was change out the sim card holder and the sim card lights up.

Hi Rique,

It seems my issue its also with the card holder. I have soldered some cables from the HL7800 directly to the SIM without any card holder ( to discard the card holder issue) and it works.

I am going to check my design, maybe there is some issue with the card holder library. Not sure yet. The card holder I am using is this one: http://katalog.we-online.de/em/datasheet/693043020611.pdf


Are you setting the sim up in anyway?
I get two voltage spikes from 0 to 1.8V that lasts for about 50ms.

when I try to do the AT+CCID?, I still get ERROR

No, I didn’t do anything to set it up.
I have just solder some wires from to the corresponding SIM contacts. If you are seeing two voltage spikes and then you don’t see anything that could mean that the negotiation at 1.8V has failed.

ETSI TS 102 221 describes the procedure for switching (and thus finding the appropriate) supply voltage in section 6.2:

6.2 Supply voltage switching
The terminal shall initially activate the UICC with the lowest voltage class available. If no ATR is received, the UICC shall be deactivated and activated with the next higher class, if supported by the terminal. If an ATR is received at the first applied voltage class, the contents of the ATR shall be analysed by the terminal. If the operating class used by the terminal is not supported by the UICC, the terminal shall deactivate the UICC and activate it with a supply voltage class indicated by the UICC. If the ATR is corrupted, the terminal shall perform the procedure at least 3 times using the same operating class before rejecting the UICC. In case of 3 consecutive corrupted ATRs, the terminal may activate the UICC with the next higher class. The terminal is restricted not to use but the next higher class in the retrial attempt in this case.

And the HL7800 only supports only1.8V sim

The USIM1 interface allows control of an only 1.8V USIM and is fully compliant with GSM 11.11 recommendations concerning USIM functions.

So my guess is something is wrong in the connection. My current connections(that I have manually soldered) from the hl7800 directly to the sim card is:


So maybe there is something wrong in your connection IO/CLK or RESET connections. The problem I had is that the library of the sim card holder I made in Altium had the wrong pin numbering.

Also you could check using AT+KSIMDET and at+ksimsel your selection. I found this newer AT reference guide somewhere in the forum.
AirPrime - HL78xx - AT Commands Interface Guide - Rev8.1.pdf (1.9 MB)

Hope that helps!

Ivan Bello
Walnut IoT

solved my problem. Bad SIM cards.