1. Kernel Config:
set CONFIG_TIMER_STATS=y Collect kernel timers statistics. can use /proc/timer_stats

2. Using Linux interval timer

3. Accessing SPI

4. Accessing I2C

reference:
[1]. https://elinux.org/Kernel_Timer_Systems
[2]. https://forum.armbian.com/topic/1901-patch-for-quick-interrupt-handling-on-the-h3-fast-gpio/
[3]. https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842191/Linux+GIC+Driver, the documentation of linux interrupt controller
[4]. http://cs.brown.edu/courses/csci1680/s22/content/threads2.pdf

---

TODO:
# Isolating CPUs Using tuned's isolated_cores Option

The initial mechanism for isolating CPUs is specifying the boot parameter isolcpus=cpulist
use [cat /proc/cmdline] to see the boot argument

https://forum.armbian.com/topic/12922-how-can-i-set-isolated-cpu-on-orange-pi-zero/

https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux_for_real_time/7/html/tuning_guide/isolating_cpus_using_tuned-profiles-realtime

https://forum.armbian.com/topic/1901-patch-for-quick-interrupt-handling-on-the-h3-fast-gpio/

https://forum.armbian.com/topic/1885-rt-patches-for-sun8i-kernel/

# https://0xax.gitbooks.io/linux-insides/content/Timers/linux-timers-4.html
# https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842191/Linux+GIC+Driver, the documentation of linux interrupt controller
# https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux_for_real_time/7/html/reference_guide/chap-hardware_interrupts

# https://www.kernel.org/doc/html/v4.14/driver-api/spi.html, SPI programming

# setitimer

# SPI

https://github.com/azorg/spi/blob/master/spi.c

# I2C

https://elinux.org/Interfacing_with_I2C_Devices

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话说2018年春节的时候，3d打印了一个机械臂。

还是老样子，在纸上先画一个机械臂大概的形状

在CAD中画出具体参数，看看用什么养的配置比较合适，作业半径会是多少。 

确定参数就可以开始做三维建模。

一步一步开始搭建机械臂的每个部分。

底座

第一关节

第二关节

第三关节，上面可以安装夹具

所有的配件就是这些

机械手臂上当然是要有手了 XD

用机械手来帮你选一瓶饮料

还是再切一个合适的手给机械臂

当然机械臂也可以很欢乐

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第一季6期的荣誉之战终于杀青了，从夏天拍到了冬天。

看看导播室里的工作场景。

刚刚停电恢复，好几个摄像机还是黑屏。

为了游戏的需要，连夜修改程序。

看到一个通信的大家伙，就是天线比较粗，比较长。

屏幕上显示了一些射频的参数，不知道是发送什么。

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The post 2014科研类全国航空航天模型锦标赛 appeared first on HE Qichen's Hackspace.

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./eagle: error while loading shared libraries: libjpeg.so.62: cannot open shared object file: No such file or directory

显然，第一步想到的就是安装lib

$ sudo apt-get install libjpeg62

但是，看到libjpeg已经安装过了，而且问题依旧。google之，发现可能由于eagle用到的是32位的库。那么就需要加上32位的限定了

$ sudo apt-get install libjpeg62:i386

安装后，eagle成功运行，问题解决

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Shanghai Sandwich is the perfect breakfast in Shanghai! It is one of the most famous local dishes with long tradition and full of flavors. Our project uses littleBits to help to make a perfect Shanghai Sandwich.

Instructions

1. Step 1. Get all the ingredients and materials ready. See the illustration we had as the recipe for the Shanghai Sandwich.

1. Step 2. Make the CiFanGao(rice patties). Shanghai Sandwich use pan to deeply fry sticky rice patties. We usually turn cooked sticky rice into delicious small blocks(dimension: 10cm/7cm/1.5cm). It is perfect golden and crispy. Itself, is one of the most popular breakfast choices for Shanghainese.

2. Step 3. No Sandwich can be perfect without tomatoes. The perfect slices of tomatoes have to be consistent in its thickness. We took the help from littleBits to build a Perfect Cutting Board. The circuit is power+bending sensor+wire+bargraph. Based on different bending angle the bending sensor creates, the different number of LEDs can be lighted up on the bargraph bit. We found out this system can be used to measure the thickness for cutting perfect slices of tomatoes. According to the order for the 5 LEDs to light, we can lean the kitchen knife to the bending sensor. While each LED light up, it approximately gives a 10mm slide of thickness every time from the tomato.

3. Step 4. Everyone loves eggs. We want to add another typical Shanghai breakfast to our sandwich, which is called JiDanBing(like Omelet). Instead of using the traditional egg beater, we'd love to create one by ourselves. We used power+wire vibration motor+wire+vibration motor to build the circuit. We took a wood stick, two rubber band and a bended cotter to make the littleBits' egg beater. It turned out working really well!

4. Step 5. Even though ChaShao(Chinese BBQ pork) can be made at home but the process is difficult and time consuming. We buy ours from famous local Cantonese restaurants.

5. Step 6. Finally we wanna add some XiangCai(parsley) to add more texture and flavors.

6. Step7. Once we have all ingredients, we layer them one after another to make the Shanghai Sandwich.

7. Step 8. A perfect dish would of course needs a perfect waiter. We made our own littleBits' waiter to serve the sandwich. It was made by power + sound trigger + wire + DC motor+wire+DC motor. We used 2 Pololu wheels and an orange juice cap as the little car's wheels. Used layers of foam core to hold the plate for the sandwich. It will run to serve once we make a sound.

Credits

David Li, Nret Ni, Qichen He

Bits used (10)

• bargraph 1
• bend sensor 1
• dc motor 2
• power 1
• sound trigger 1
• vibration motor 2
• wire 2

Other Materials Used (15)

• Chinese BBQ pork 1
• cutting board 1
• double side tape 1
• eggs 1
• electric wire 1
• foam core 1
• oil 1
• orange juice cap 1
• parsley 1
• Pololu wheel 2
• rice 1
• rubber band 4
• third hand 1
• tomatoes 1
• wood stick 1

Tools (2)

• frying pan
• knife

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