SL8090 with development kit

I have an SL8090 attached to the SL series development kit. The modem has been inserted and the onboard switches are set as specified in “AirPrime_SL_Series_Mechanical_Socket_Development_Kit_Quick_Start_Guide_Rev3_0.pdf”. I’m hoping to use this modem to replace our aging WISMO228 design and bring 3G capability to our telemetry.

I’ve been connecting to the SL8090 via the development board UART and I’m having some problems (they seem to exist via USB as well).

I can’t get the modem to echo characters sent to it. I’ve sent ATE1 which the modem acknowledges but then doesn’t act on. I’ve tried an AT&W to save the configuration followed by a reset to no effect.

The modem interface seems to go into some kind of sleep mode after a couple of seconds. When this happens an has to be sent before an AT command is registered. I’ve check the modem isn’t set for auto baud detection just incase this was the cause. Is there a way to stop this?

The modem returns an error when I try an enable AT+CFUN=1. There’s a SIM card attached and AT+CPIN returns “Ready”. AT+CSQ returns 99,99 which would indicate no signal although there clearly is when I survey the site with my phone.

I hope someone can help, it’s driving me nuts I can’t get past the basics to start experimenting with the PAD commands!



It looks like the UART sleep issue can be fixed by using AT+WHCNF and deactivating the sleep flag. Still no luck with enabling echo though and I realise it also fails to echo result codes if they don’t begin with “+”

I realise I’m replying to my own old post here but I came up with solutions and figured they might be useful for someone.

Firstly, the development kit for the SL8090 modem really means it when it specifies a 4V @ 2A supply. The 4V supply I was using came in at around 4.3V and that was enough for the modem to refuse to start full functionality (AT+CFUN=1 created an ERROR). Typing:


Showed the “Volt” parameter as 1, indicating an issue. Changing the supply to be bang on 4V brought everything to life.

I had a real problem with the UART going to sleep with no activity after a few seconds. The UART was woken again by typing, however several characters would get “absorbed” before the system returned fully to life. I found this did the trick:


Then reset the modem for UART sleep to be disabled.

The Echo issue was resolved by resetting to factory defaults.

Hope that helps someone!