diff --git a/README.md b/README.md
index e8d33d2..72a56b1 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,81 @@
 # Flash Tool for Aruba AP-105
 
-Tool to exchange Aruba AP-105 boot loader with uboot for flashing OpenWRT.
+Tool to exchange Aruba AP-105 boot loader stored on a MX25L12835 flash chip with uboot for flashing OpenWRT with an RaspberryPi.
+
+## Prepare
+
+Requirements:
+
+- RaspberryPi
+- Programming clip SOIC16/SOP16 and cabling
+- [Raspbian](https://www.raspberrypi.com/software/)
+- [enabled SPI interface](https://codingworld.io/spi-aktivieren-am-raspberry-pi/)
+- [`flashrom`](https://www.flashrom.org/Flashrom) tool
+
+Configure SPI on the RaspberryPi:
+
+```
+sudo raspi-config
+# Select Interfacing Options
+# Select SPI 
+# Select Yes
+# Select Ok
+# Leave with finish or ESC
+```
+
+To install `flashrom`:
+
+```
+sudo apt-get install flashrom
+```
+
+Connect the AP105 Flash chip. The red status LED on AP105 must glow
+
+```
+        *-------------------------------------*
+        |                                     |
+        |          ------|MX25L12835------    |
+        |         |                       |   |
+        |   *-----|1 HOLD#/SIO3    CLK 16 |---|----*
+        |   *-----|2 VCC       SI/SIO0 15 |---*    |
+        |   |     |3 RESET#               |        |
+        |   |     |4                      |        |
+        |   |     |5                      |        |
+        |   |     |6                      |        |
+        |   |  *--|7 CS#           GND 10 |------* |
+        | *-|-----|8 SO/SIO1     WP#/SIO2 |-*    | |
+        | | |  |   -----------------------  |    | |
+        | | |  |                            |    | | 
+        | | *-------------------------------*    | |
+        | | |  |                                 | |
+        | | |  *-------------------------------* | |
+        | | |                                  | | |
+        | | |    --------|RaspberryPi|-------  | | |
+        | | |   | 1                         2| | | |
+        | | |   | 3                         4| | | |
+        | | |   | 5                         6| | | |
+        | | |   | 7                         8| | | |
+        | | |   | 9                        10| | | |
+        | | |   |11                        12| | | |
+        | | |   |13                        14| | | |
+        | | |   |15                        16| | | |
+        | | *---|17 +3V3                   18| | | |
+        | *-----|19 MOSI/GPIO              20| | | |
+        *-------|21 MISO/GPIO              22| | | |
+          *-----|23 SCLK/GPIO  GPIO 8/CE0# 24|-* | |
+          | *---|25 GND                    26|   | |
+          | |   |27                        28|   | |
+          | |   |29                        30|   | |
+          | |   |31                        32|   | |
+          | |   |33                        34|   | |
+          | |   |35                        36|   | |
+          | |   |37                        38|   | |
+          | |   |39                        40|   | |
+          | |    ----------------------------    | |
+          | |                                    | |
+          | *------------------------------------* |
+          *----------------------------------------*
+```
 
 ## Usage
 
@@ -17,7 +92,28 @@ The `AP105-<SERIAL_NUMBER>-dump0.rom` will be patched with uboot binary `uboot.b
 
 After a confirmation the patched file will be flashed to the device.
 
+## Known problems
+
+### Chip isn't detected by flashrom
+
+- Check the wiring
+- Ensure the RaspberryPi have enough power like a power supply with 5V/2A
+- Ensure the red LED is illuminated on the AP105
+- Reduce the SPI speed to 1000 kHz (default 16500 kHz)
+
+```
+SPEED=1000 ap105-flash <SERIAL NUMBER>
+```
+
+### flashrom fails during erase
+
+- Check power supply
+- Reduce the SPI speed like described above
+
 ## Sources
 
 - [git repository for uboot loader @chunkey](https://github.com/chunkeey/u-boot-ap105/releases)
 - [OpenWRT device page](https://openwrt.org/toh/aruba/ap-105)
+- [Datasheet MX25L12835](https://pdf1.alldatasheet.com/datasheet-pdf/view/575542/MCNIX/MX25L12835E.html)
+- [RaspberryPi ASCII Art](http://weyprecht.de/2015/11/30/raspberry-pi-ascii-art/)
+