LED名片拆解

最近買了一個LED名片, 想了解一下他的驅動方式, 買回來第一天就被我分屍了, 分屍前的照片還來不及拍... 只剩下這張屍塊組合照...

這咚咚是超音波熔接的, 非常難拆, 只能慢慢用筆刀劃開, 再用一字起子撬開.....

前方搭載了紅色濾光片, 對於判讀起了非常大的幫助, 若沒有濾光片, 光是LED本身的反光就夠亮的了.

濾光片完全拆除, 字幾乎看不清楚...

再來是最重要的背部, 很可惜不是採用ATMEL的solution. 採用的是GD32F150/C8T6的ARM mcu: http://www.gsense.com.cn/pro_detail.asp?id=139

LQFP封裝, 48pin, 支援高達39個GPIO.

本來以為買來會是採用ATMEL的solution, 這樣就可以把ATMEGA mcu刷成Arduino來玩玩了. 但是ATMEGA就沒那麼多IO可用, 所以要配置可觀的74HC595(就圖上應該有6顆), 如此cost也就低不下來.

以這個LED名片來看, 是四字的配置, 高度為11點, 因此總共有11x11x4 = 484點.

以傳統的掃描驅動方式需要44個IO(22x22 = 484).

ATMEL搭配6顆74HC595的, 每顆74HC595可以將3個IO擴充成8個IO, 因此18個IO可以擴充成48個IO, 可以驅動多達 24*24 = 576顆LED. 因此應付這個LED名片的484點是足夠的.

反觀GD32F150也無法驅動這麼多LED, 但也沒看到其他IC, 因此可能採用的就是Charlieplexing的驅動方式. 應用Charlieplexing只需要23pin就可以驅動507顆LED(23*23-23 = 506), 對GD32F150來說提供23個IO綽綽有餘.

雖然GD32F150 cost低, 但是採用的Charlieplexing本身掃描頻率比Multiplexing高很多, 但也因此單位時間內的LED發光次數會降低, 也就是LED亮度會比較低.

有機會再找找ATMEL solution的LED名片來分屍!

Use Arduino STM32 with Maple mini

Maple Mini

Maple mini is a phased out product, a STM32 based product with cheap price(about 5USD or 150NTD).
Official Maple IDE is not bad, but no longer support to win7, and driver with IDE is not signed, win7 deny install the driver without signed. It make Maple mini be a junk after win xp os.

Arduino  STM32

There are some replacement package can let maple mini alive with win7 os:

1. Arduino Support Package For Maple
2. STM32F103 and Maple / Maple Mini with Arduino 1.5.x IDE
3. Arduino STM32

The best choice is method 3: "Arduino STM32", because it's based on method 1&2, and still active project.

It's a package to run with Official Arduino IDE, so you need to download the Arduino IDE and install. The newest version 1.6.7 maybe is not a good choice, because I had some problem when compiling sketch. Version 1.6.5 is ok and Arduino STM32 official site say support it.

Install Arduino STM32

Download Arduino STM32 and decompress, recommend to put whole directory to "~your sketch directory/hardware/" , named it to "Arduino_STM32" or whatever you like.

Install the driver first by "Arduino_STM32/drivers/win/install_drivers.bat".

Run Arduino IDE, now you can seed Maple Mini in Board:

Bootloader

If your Maple Mini is original, you should select Original Bootloader.

 

It's recommend to update to Bootload 2.0 (bootload with Arduino STM32).

You can update by a updating sketch  from Arduino STM32's site. You can download it by this link. And Follow these step:

1. Upload "updating sketch" by Arduino IDE with Original Bootloader version.
2. Open Serial Monitor, you can see some warning message, press Y and send it.
3. Wait some updating message, reset it, 

Now you have Maple Mini with Bootloader 2.0.
Happy Arduinoing with Maple Mini !!!!