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Team 7700B Texas Instruments Electronics Online Challenge: VEX Cortex Dissection


Entry ID #: 2442
Created: Tue, Jan 12, 2016 10:25 PM

The electronic device we decided to take apart is a VEX cortex. The reason why we chose the VEX cortex, was because all VEX robots depend on a VEX cortex during the competition.  The cortex that we used had a short circuit that occurred during a competition, and under further external inspection, we found that ports 7,9, and 10 stopped working.  Opening this cortex also gives us an opportunity to see what happens inside a VEX cortex (Fig. 1). Under initial interior inspection, we noticed that a motor controller chip connected to port 10 was melted (Fig. 2), and that the plastic underneath the PCB was burnt. Unfortunately, we can’t use this cortex anymore. We found a Hex Inverter (Fig. 3) made by Texas Instruments. It is AD04 containing six independent inverters which invert six digital signals simultaneously. This is a sub package of SN54ACT04.  This makes sense, because the chip is right next to the digital ports, to invert the digital signals. In addition, we found 3 main chips in the cortex. The first is an STM32F103 which is the ARM® 32-bit Cortex®-M3 processor (Fig. 4). It can run up to 72 MHz, with 16K-1M of Flash storage, and has 6-96 kB of RAM. This processor is used to interpret programs and send signals based on the programs to output ports.  The second chip is a LPC2458FET180 microcontroller made by NXP (Fig 5). It runs up to 72 MHz, has 512 kB flash memory and 98 kB of SRAM. It stores the programs and communicates with the ARM cortex. The third chip is a CY62157EV3 (Fig. 6) made by Cypress Semiconductor. It has static RAM which provides 512 kB of RAM, which the entire cortex uses. In conclusion, we learned that the VEX cortex is extremely complex, with several different chips allowing for many different processes. *If you cant see the photos, please scroll down to the Files/images section. Fig. 1: The front and back sides of the cortex PCB The pictures in Fig. 2 to Fig.6  are taken by by 20X microscope camera. Fig. 2: The motor controller chip was melted.   Fig. 3: The Hex Inverter made by Texas Instruments found in VEX Cortex.  Fig. 4: ARM® Cortex made by STMircoelectronics.  Fig. 5: Microcontroller - LPC2458FET180 by NXP.  Fig. 6: SRAM CY62157EV3 by Cypress Semiconductor.    


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