The task of this week was completely different. We were asked to do some engineering design work .The client company wants to build a device that has the following:

  • CPU + RAM

  • SD card

  • Wifi/GSM

  • Camera

  • Battery

So our task was to pick up the suitable components based on the requirements given. The camera for example was requested to have a frame size of 800×600 and the ability to take 25 frame per second. The task was not easy as it may sound. The task is not just simply blindly picking random components .. it’s about picking the RIGHT component that meets the requirement and matches with other components without exceeding the boundaries.

At first we met with Dr.Shawn and we discussed the physical limitation we have. Each one of us was requested to come up with at least three designs.

The camera output is our system input, it has frame size 800×600 @25 fps. Meaning that the camera will produce at least 288 Mbps. Knowing this, the other component like GSM and Wifi modules or modems should have the ability to transfer the data at suitable data rate (speed).

Working with each device helped me understand what specification I should look at in that component, the technologies behind it and the way it can be interfaced with other components. For example, when we were looking for GSM module or modem I had to read first about the different wireless technologies. Starting from the 1st generation to the 4th generation or what’s known by (4G). Understanding the maximum speed they can provide and choosing the one that suits the video streaming the most. In Malaysia for example most of the telecommunication companies already offer the 4G technology (LTE) which has at least 50 to 70 Mbps uplink speed. Knowing the limits we have, now we started to look for either module or modems that enables us to transfer our data with that speed. Following the same process with other components we finally managed to come up with three designs.

In this week also I came across the concept of serial communication and its protocol such as SPI , I²C and USB. SPI which stands for Serial Peripheral Interface is a communication protocol which is based on three wires communication system. One wire each for Master to slave and Vice-versa, and one for clock pulses. There is an additional SS (Slave Select) line that is used for transmitting data between multiple ICs . I²C (Inter-Integrated Circuit) on the other hand has two wires , on for the clock and other for data transmission. Its speed is quite small and usually used for control. Lastly the USB or Universal Serial Bus. It has 4 wires (Data-Data-VCC-and Ground).  Understanding each protocol and the limitation it has helped me decide which module or components we should use.

Finally, Taking all the physical limitation of all components into account, the type of CPU is then determined based on the number of pins needed,the amount of computational power,..etc.

At the end of the the week we managed to come up with many different designs. When you look to that simple table that we finally came up with , you may underestimate the amount of effort and time needed to accomplish this task but I really believe that the true treasure is not in the final result but on the journey the person takes to reach that treasure the knowledge he gains and the experience he lives 😉 .

1 Comment

Embedded System Design | AESTE · 2015-03-23 at 13:52

[…] is no point of listing all the components we considered, and Sumia did a great job explaining most of them here, but I’ll give a brief explanation of some of the stuff I did. We started with the camera, as […]

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