Description (From Recipaedia )
An electric 4 bit counter with increment, decrement, reset and overflow detection capabilities (useful for chaining counters). Outputs its current value at the top via an analog signal. You can use analog-to-digital converter to extract the actual 4 bits, if needed. Signal on the right input increments the counter. Signal on the left input decrements it. Both increment and decrement wrap aroung when reach above 15 or below 0, in which case an overflow signal is generated at the bottom output. The back input (use wire-through-block element to access it) resets the counter to 0. Plus, minus and reset input are activated by rising edge of the signal. The counter can be mounted on any vertical surface and rotated to desired orientation.
Crafting
Use 2 copper ingots and 5 germanium crystals to craft the 4-bit counter. You get 4 counters chips.
Hooking it up
There are 3 inputs to the counter and 2 outputs. Typically only 1 of the inputs and the analog output will be used in most applications. Typically.
The 3 inputs + (INC), - (DEC) and RESET are common digital signals and can be controlled by a switch or pressure pad or any other digital output. The reset input is on the back of the chip so you have to use a wire-through block to get to it.
The main output - C is analog and must be fed to an analog input of another device. It has a value from 0 - F which increases by one every time the + input activates (the rising edge). It decreases by one when the - input goes high. When the reset input goes high, this output goes to 0.
The O (OVERFLOW) output is also a digital signal and can energize a LED or a light or activate a door or be fed to any other digital input. If the value of the counter tries to go less than 0 OR greater than F then the Overflow output will go high (until any input changes < must be verified >). This may be used to 'chain' counters to let you count to much bigger numbers. This output would go into the next counter's input.
Uses
The 4-bit counter is typically used for --- counting.
You could use it in a circuit that only lets someone enter a room 3 times then it will drop a column of sand in front of the door.
Use it with a date clock circuit to count the number of days you have been in a mine.
They are a necessary component in combination or PIN type locks.
Applications
Short Counting
You may need the counter to only cycle through a smaller number and stop. This may be done with a few added gates. For an UP ONLY counter, add an AND gate in series with the + input, feed the counter output to a Memory Bank which was programmed as a compare and take the output of the bank to the other side of the AND. Program the bank to disable the AND when you reach the maximum number of the count.
If you short the count on an UP/DOWN counter, you must also limit the down count so it will stop at '0'. Use the same technique but program the bank differently. The counter in the image above has both limits.
Extended Up/Dn Counting
The overflow output may be used to extend the counter for a dedicated up OR down counter but cannot be used in a single Up/Dn counter because it does not distinguish between an UP overflow and a DOWN underflow. The following circuit does this.
The memory banks are programmed to detect the overflow (carry) and underflow (borrow) conditions. For example when the new count is '0' and we are counting UP, the counter has overflowed (carry) and the bank on the right sends an UP count to the next higher stage (top center of the image). The memory bank for the borrow condition is programmed similarly. The two OR gates are necessary to allow the counter to update its output before the carry or borrow is determined.
Notes
- For more advanced counters which do NOT use this chip, see Counter Circuits.
- Despite Recipaedia's description, 4-bit Counters can be placed on horizontal surfaces too since v1.29.
History
The 4-bit counter was added in ver. 1.23