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Code Examples

Esteemed Contributor

For a long time I was wondering how a weight scale is working.

And when I found a miniature loadcell at Akizuki, which is one of the nerd's sanctuaries in Akihabara, I decided to play with it.

IMG_2526.JPG

According to the datasheet of the loadcell the output is 0.7+/-0.15mV/V for input 3.0~10.0V.

If I run CY8CKIT-044 in 3.3V mode, the output will be around 2.3mV.

If I connect the output directly to the ADC input, it won't show much resolution.

So I decided to take advantage of Opamp in the PSoC 4.

After some (lots of) try and error, I ended up following schematic.

circuit.JPG

The result Tera Term log, the left side is direct connection from the loadcell to ADC input,

and the right side is the data through Opamp.

And when I pushed the loadcell the ADC value changes only 0~3,

and value read through Opamp changed 1~1600.

So I hope that I can conclude that the Opamp is doing its work.

teraterm_log.JPG

moto

2 Replies
Honored Contributor II

Motoo,

Sweet memories... Akihabara was great! I assembled my first computer (x486) from parts there. Many moons ago...

Thank you for sharing the project.

/odissey1

Esteemed Contributor

本サンプルは CQ出版 インターフェース 11月号に

 重さや力を測る定番センサ・デバイス・・・ロード・セル

として掲載されました。

I contributed this sample project to a Japanese

technical magazine "Interface" Nov. edition.

http://interface.cqpub.co.jp/magazine/201811/

moto

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