By tokala - Tue Apr 02, 2019 3:50 am
- Tue Apr 02, 2019 3:50 am
#6909
Just to clarify, this is the GPS board from the green box from the front of a Lime.tokala wrote: ↑Sun Mar 31, 2019 2:15 amHello everyone
I thought I would share what I’ve found on the Lime GPS/Cellular module so far. I was given two Lime front green boxes to play with.
The green box contains two boards, the larger board contains the main processor, Bluetooth module, GPS module and voltage regulators. The smaller board looks like it is simply a voltage regulator, dropping the battery voltage down to 5V.
The main chip on the SLT181 board is a MeiG Smart SLM750 LTE (cellular) chip with UART (Serial), USB 2.0, Bluetooth HCI and I2C interfaces. The CPU is a Qualcomm ARMv7 and is running a Linux 3.18 Ubuntu kernel.
[ 0.000000] Booting Linux on physical CPU 0x0
[ 0.000000] Initializing cgroup subsys cpu
[ 0.000000] Initializing cgroup subsys cpuacct
[ 0.000000] Linux version 3.18.20 (xiaoqinqin@ubuntu-241) (gcc version 4.9.2 (GCC) ) #1 PREEMPT Thu Aug 16 17:16:19 CST 2018
[ 0.000000] CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=10c53c7d
[ 0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
[ 0.000000] Machine model: Qualcomm Technologies, Inc. MDM 9607 MTP
[ 0.000000] Early serial console at I/O port 0x0 (options '')
[ 0.000000] bootconsole [uart0] enabled
[ 0.000000] Memory: 148036K/257024K available (8204K kernel code, 1096K rwdata, 3668K rodata, 348K init, 1156K bss, 108988K reserved)
The board also contains a SIM card on the bottom. The SIM is from Twilio who offer a “super sim” which can be used internationally to send data via SMS or Mobile data.
https://www.twilio.com/wireless/super-sim
I powered the board with a USB to Serial converter connected to the serial pins of the plug. I have included the pinouts that I know so far.
The issue I have is that the chip boots until I get “Error code 303e at boot_flash_dev_nand.c Line 571”
The chip has NAND flash on board so I’m not sure if the error is referring to the on-chip NAND or if it is trying to contact storage elsewhere on the same or another board?
If I drop the Serial TX to earth for 2 seconds at boot, I can put the SLM750 into a programming mode and get an almost full boot. If I earth out Serial TX for 5 second-ish, I get a different boot sequence but both end with a kernel panic and a reboot back to the error code 303e.
The links below are to Pastebin showing the default boot, the 2 second earth and the 5 second earth.
Default boot: https://pastebin.com/PiV3xiGS
2 second earth: https://pastebin.com/eCA5VPx8
5-ish second earth: https://pastebin.com/ed85ceeQ
This is the pinouts of the main plug on the main board.
If anyone has anything to help me get the chip to fully boot I would like to hear from you.