NuttX Channel: Getting Started to NuttX

I create a NuttX Channel in Youtube to let more people to know about NuttX and to use it.

This series has 4 videos to let you configure and test NuttX on STM32F103 Minimum board:

Video 1:

Video 2:

Video 3:

Video 4:

I hope you enjoy it!

pdfcrack can find the numeric password of my bank pdf file credit-card bill in less than 1 second

Every month my bank sends me a PDF file with all my credit card expenses. Then normally I save these files. Today I tried to open an old file (more than 3 years), but I cannot recall the 4 numeric digits to open it.

Then I decided to use the pdfcrack tool to help me on this.

First, this file password is only 4 digits based on the credit card number:

xxxx xxxx XXXX xxxx

I can to instruct pdfcrack to only use numeric characters to test the password, passing “-c 0123456789”. Also because the password is 4 digit fixed I need to instruct pdfcrack to avoid testing password lesser than 4 chars using “-n 4”.

So that is it:

$ pdfcrack -f filepass.pdf -c 0123456789 -n 4

PDF version 1.4
Security Handler: Standard
V: 2
R: 3
P: -4
Length: 128
Encrypted Metadata: True
FileID: ddcb8e715b3c7347822d9548344a5964
U: ae718555d827f01765d0da553e9675e228bf4e5e4e758a4164004e56fffa0108
O: f86379060fbc201da762108dcdfe7846d1625dae9b9422e8d8fa7687eee97d05
found user-password: '7867'

I just pressed <ENTER> and it returned the password! Incredible!!!


Flashing firmware with OpenOCD without using telnet

Normally I use OpenOCD to flash firmware on my microcontrollers, but always use telnet to connect to openocd server in the port 4444.

Today I realized it is not necessary to use telnet to flash the firmware, I can do it from command line:

$ sudo openocd -f interface/stlink-v2.cfg -f target/stm32f1x.cfg -c init -c "reset halt" -c "flash write_image erase nuttx.bin 0x08000000"

I used this command to flash the nuttx.bin firmware on STM32F103 Minimum board. This is the “openocd_stm32f1.cfg” config file content:

# STM32F103Minimum Board

# Using stlink as SWD programmer
source [find interface/stlink-v2.cfg]

# SWD as transport
transport select hla_swd

# Use STM32F103C8 target
source [find target/stm32f103c8t6.cfg]

MC900 Mini Camera AV-in JACK Pinout

I bought a MC900 Mini CCTV Camera from DealExtreme two years ago and never got the chance to test it. Then today finally I decided to test it.

Unfortunately the single page manual that came with it is really bad. There are description about two models: MC900 with just the camera sensor and two small boards exposed and MC900D a complete enclosured camera box. The later was the model I bought.

My model came with an AV 3.5mm jack and can be seen here:

After some tests I figured out the correct pinout:

Fortunately the new MC900D-V9 model already come with RCA connector and power supply, but it is big and doesn’t have audio, as you can see here:

This camera is small and good for spy application, but it is not color video.