diff --git a/README.md b/README.md
index 30db277..9474bdb 100644
--- a/README.md
+++ b/README.md
@@ -42,7 +42,7 @@ DRV8825 stepper motor driver (using one timer for PWM output):
 reed switch:
 
 - 1: GND
-- 2: PB3
+- 2: PB4
 
 LED driver (using one timer for PWM outputs):
 
@@ -51,6 +51,10 @@ LED driver (using one timer for PWM outputs):
 - gate 2: PB8/TIM4_CH3
 - gate 3: PB9/TIM4_CH4
 
+WS2812b LED matrix:
+
+- DOUT: PB5 (SPI1_MOSI)
+
 RGB matrix (using one DMA)
 
 - DR1: PA2
@@ -67,11 +71,41 @@ RGB matrix (using one DMA)
 - D: PB3
 - OE: PB10
 
-ESP8266 (using one UART):
+ESP8266-based ESP-01 (using one UART):
 
 - RX: PA9/USART1_TX
 - TX: PA10/USART1_RX
 
+EN is pulled to VCC using 10 kOhm for the ESP to start.
+I replaced the 1 MB flash with a 4MB flash to be sure I won't be annoyed by the space limit.
+I flashed the AT firmware from ESP8266_NONOS_SDK-3.0.5:
+
+~~~
+esptool.py --chip auto --port /dev/ttyUSB0 --baud 115200 erase_flash
+esptool.py -p /dev/ttyUSB0 --chip esp8266 write_flash -fm dio -ff 26m --flash_size 2MB-c1 0x00000 ./bin/boot_v1.7.bin 0x01000 ./bin/at/1024+1024/user1.2048.new.5.bin 0x1fc000 ./bin/esp_init_data_default_v08.bin 0xfe000 ./bin/blank.bin 0x1fe000 ./bin/blank.bin 0x1fb000 ./bin/blank.bin
+~~~
+
+to test the firmware, issue AT commands:
+
+~~~
+picocom -b 115200 /dev/ttyUSB0 --omap crcrlf
+AT
+
+OK
+
+AT+GMR
+version information
+~~~
+
+configure the access point in flash:
+
+~~~
+# set station mode
+AT+CWMODE_DEF=1
+# set AP credentials
+AT+CWJAP_DEF="essid","password"
+~~~
+
 free:
 
 - PB4, PB5