User Tools

Site Tools


8devices Carambola 2

Carambola 2 board


  • 802.11 b/g/n, 2.4 GHz, 1x1 SISO, 150MBps max data rate, 21 dB output power
  • U.FL connector or external pin for external an­tenna
  • 16 MB FLASH, 64 MB DDR2 RAM
  • CPU – AR9331, 400 MHz clock speed
  • 28 by 38 mm Size – small and easy to embed
  • Surface mountable
  • Power supply - 3.3 V, power consumption 0.5 W
  • Available interfaces - USB host/slave, serial port, 2 x Ethernet, i2S, SLIC, SPDIF, 23 x GPIO

Serial connection

Serial connection settings:

  • 115200 8N1, no hardware flow control.


Works via the built-in miniUSB port:

apt-get install picocom
picocom -f n -p n -b 115200 -i -r -l /dev/ttyUSB0

Upgrading OpenWrt


Bootstrap HIGH or LOW means that during bootstrap process (first few seconds as device is turned on) these pins need to be in that state. If pins are not in requred state then device will not boot correctly.

Worry free GPIO pins™: If you have some DIY project use GPIO pins 18, 19, 20, 21, 22 and 23 without any worries, these pins are not used during booting. Other GPIO pins are not suitable for use if you don't know exactly what you are doing because they are used during boot process (bootstrap).

LED GPIO LED0 (GPIO0), LED2 (GPIO13) and LED3 (GPIO14) are being used by kernel module "leds_gpio" - You can use them after removing leds_gpio module by rmmod, or removing it permanently from /etc/modules.d

Carambola 2 pinout

GPIO Pin Input/Output Bootstrap Name Description
Gpio 0 41 output Must be HIGH during bootstrap Wlan led, LED0 10K pull-down output
Gpio 1 40 bidirectional Must be HIGH during bootstrap LED1 10K pull-up output, input goes to ground
Gpio 11 23 input soft reset 1K and 100pF input, reset if connected with GND
Gpio 13 39 output Must be HIGH during bootstrap Eth0 led, LED2 10K pull-down output
Gpio 14 38 bidirectional Must be LOW during bootstrap Eth1 led, LED3 10K pull-down output
Gpio 15 37 bidirectional Must be LOW during bootstrap LED4 10K pull-down output
Gpio 16 36 bidirectional Must be LOW during bootstrap LED5 10K pull-down output
Gpio 17 35 output Must be HIGH during bootstrap LED6 10K pull-up output
Gpio 18 6 bidirectional I/O line number 18
Gpio 19 5 bidirectional I/O line number 19
Gpio 20 4 bidirectional I/O line number 20
Gpio 21 3 bidirectional I/O line number 21
Gpio 22 2 bidirectional I/O line number 22
Gpio 23 1 bidirectional I/O line number 23

Bootstrap hardware initialization

AR9331 datasheet mentiones these GPIOs used by hw initialization:

  • GPIO0 : crystal frequency 25 /40 MHz
  • GPIO1 : booting from internal ROM / Flash
  • GPIO 12/28 : external memory type (SDR, DDR, DDR2)
  • GPIO16: download firmware from USB/MDIO
  • GPIO13: USB mode device /host

Default FLASH Layout

mtdparts=spi0.0:256k(u-boot)ro,64k(u-boot-env)ro,2048k(kernel),13888k(rootfs),64k(nvram),64k(art)ro,15936k@0x50000(firmware) … m25p80 spi0.0: found w25q128, expected m25p80 m25p80 spi0.0: w25q128 (16384 Kbytes) 7 cmdlinepart partitions found on MTD device spi0.0

Partition Start End Size Erasesize Name Description
mtd0 0x000000000000 0x000000040000 0x00040000 0x00010000 u-boot
mtd1 0x000000040000 0x000000040000 0x00010000 0x00010000 u-boot-env
mtd2 0x000000050000 0x000000040000 0x00200000 0x00010000 kernel
mtd3 0x000000250000 0x000000FE0000 0x00D90000 0x00010000 rootfs root filesystem
mtd4 0x000000480000 0x000000FE0000 0x00B60000 0x00010000 rootfs_data partition created automatically, ofs=480000, len=B60000
mtd5 0x000000FE0000 0x000000FF0000 0x00010000 0x00010000 nvram
mtd6 0x000000FF0000 0x000001000000 0x00010000 0x00010000 art
mtd7 0x000000050000 0x000001000000 0x00F90000 0x00010000 firmware


Debricking Carambola 2




Architecture: MIPS
Vendor: 8devices
System-On-Chip: Atheros AR9331
CPU/Speed MIPS24Kc 400 Mhz
Flash size: 16 MB NAND-Flash
Wireless: 150Mbps WiFi g/n with on-board chip antenna (21 dB output power), U.FL connector
Ethernet: 2x 10/100Base-T(X)
USB: 1x 2.0 (host), 1x miniUSB (slave)
Serial: YES (via miniUSB or RS232 (soldering needed))
LED: Standard Ethernet LED's, WIFI LED
Hardware buttons: Hardware reset button, GPIO programmable button
Power options: miniUSB jack (3.0-3.6 V)
Power consumption: ~0.5 Watt
Dimensions: mm x mm, grams
toh/8devices/carambola2.txt · Last modified: 2014/09/01 17:41 by spriver