Programmable counter controller with memory function

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Programmable counter controller with memory function [Copy link]

1. Overview:
The pulse counting controller has a wide range of uses. It can count the pulses converted from many physical quantities and output control signals. The programmable pulse counter composed of a single chip is more flexible in application. The setting of the counting pulse can be programmed (modified) by the user at any time, and the set data can be recorded. Even if the power is off, it will still take effect when the power is turned on next time. The right picture is a simplified diagram of the control function.

The whole machine is controlled by an 8-bit microprocessor HT48R05A-1, and the counting (or setting) pulse data is displayed by a 6-bit LED. To record the set pulse, we selected an I 2 C bus EEPROM (AT24C01) for recording. The next time the machine is turned on, the system will first read the set data from the memory and put it into RAM for comparison when the system is working. When the counting pulse reaches the set data, the output port outputs a control pulse (or level).

The display part uses a 6-bit seven-segment digital tube (LED). There are two circuits to choose from. One is the static display mode, which is driven by 6 74LS164s in series and out of the shift register. The advantage of this method is that the program does not need to manage the display data all the time. It only needs to refresh the display content when the data is updated. The single-chip microcomputer I/O ports used are few (only 2 are needed). The disadvantage is that the hardware expenditure is large, and a total of 6 driver chips are required. The second method is to use a dynamic display mode, using only one 74LS164 to drive the segment code, and the address line of the LED is provided by the I/O port (6) of the single-chip microcomputer for time-sharing scanning. The advantage is that the hardware is simpler (only one 74LS164 is used) and the circuit is simpler. The disadvantage is that the software programming is more complicated, and the display part needs to be managed every time, and the frequency of dynamic scanning cannot be too low to avoid flickering of the display. At the same time, more I/O port lines need to be occupied. Of course, if the I/O port line is tight, it can also be achieved by using peripheral circuit expansion (for example, using a 3-8 decoder 75LS138, etc.).

There are four buttons in the circuit, namely "SET" - setting button, "SELECT" - selection button, "COUNT" - setting button, and "CLEAR" - clearing button. "SET" is used to set the data state, "SELECT" is used to select the set LED position, "CLEAR" is used to clear all set data, and "COUNT" is used to set data. In this way, the user can set the required count value for each LED. The output is driven by a triode, which can drive a current of 12V/0.5A. If a larger current needs to be driven, the power of the power tube needs to be increased.

huchuan987

Use AT MEGA8, with built-in 512BEEPROM.

破茧佼龙

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