WEEK 5

OPERATIONS

The circuit is powered from a 9volt battery that is connected to an ON Semiconductor NCV7805 Positive Voltage Regulator to limit & stabilize the board voltage to +5.0volts. all ICs are powered from this regulated +5.0volts with the SRAM also having an additional backup CR2032 +3.0volt button battery. The CR2032 allows the main power to be shut off, while retaining all the neural network memory in the SRAM chip & not requiring the circuit to be re-trained each time the units is shut down. The microphone & the keypad consist of the only user interfaces with the circuit. The microphone is standard PC microphone which acts as the transducer converting the pressure waves to an electrical signal. The microphone is coupled to the HM2007 IC which is attempting to classify each word into the different trained categories. The keypad consists of 12 normally-open momentary contacts switches. These were soldered onto a printed circuit board which was used to communicate with the HM2007 IC. The keypad allowed the user to train the system & also clear the memory. The circuit outputs consist of the two 7-segment display & the LED. The 7-segment display shows any error codes, show the target being trained & the final classification by the HM2007system. As designed in the circuit, the top display is the most significant & the bottom is the least significant. For example, the number 9 would show a 0 on the top display & a 9 on the bottom display. Only 01 through 08 was used for this project. The LED is connected to the HM2007 IC & is used to show the status of the HM2007 IC. When the LED is on, the system is listening & will classify all incoming sounds. When the LED is off, the system has been placed in training mode, and when the LED flashes, it indicates that the word spoken was just successfully trained & placed into memory. The core component of this project was the HM2007 LSI circuit manufactured by Hualon Microelectronics Corporation.

This is complementary metal-oxide-semiconductor (CMOS) voice recognition chip that contains an analog front end, voice analysis, recognition process via neural network, and system control functions. The SRAM chip was a Hitachi HM6264LP-70. It is an 8192 word by 8-bit static random access memory with a read/write time less than 150ns. All the information from the HM2007 IC is stored off-board onto the SRAM chip. The 74LS373 is an Octal D-Type Transparent Latch. It is used to retain the binary-coded decimal (BCD) data from the HM2007 on the 7-segment display. Two 4511 CMOS ICs were also used. These are BCD to 7-segment Decoders that convert the BCD data stored in the 74LS373 to outputs capable of driving the 7-Segment Displays .One IC is used for each of the 7-Segment Displays.