Connect: Lead 74HC595 chipThe pin is connected with the digital tube, including serial input, clock input, parallel output and output enable pins. Data transmission: The single chip computer will convert the displayed numbers into binary data, and input the serial input pin to the 74HC595 chip.
First of all, you have to know that each of the eight sections of the digital tube is equivalent to a light-emitting diode LED, and the working current is about 5mA. To drive this LED, rely on single-chip IO direct output definitely not. LED drive general low-power plastic package triode (9018550, 2N3906 these) operating current is greater than 5mA,. Change the circuit board. Add a switch, 340 has been power supply, the switch is used to control the MCU power supply. However, it is said that there is also a power-free download method, that is, to change the upper computer, can not use the isp software stc.
All the keys involved should be delayed to eliminate the shake, that is, add a delay after read.
What's the use of just making a prototype... You have to look at the body of the function to determine what it does. Literally, it should communicate with CH452, writing a custom BCD code 0x05 to it.
Connection: four digitsThe tube has four selection ends, ensuring A unified time only A-G fields, only valid for one digital tube. Light the nixie tube, select A certain nixie tube by selecting different selection terminals, and light it through the A-G field.
In microcontroller control systems, keys are usually connected using GPIO pins so that the microcontroller can read the status of the keys and respond accordingly. There are usually two ways to connect keys: short-circuit and pull-up/pull-down resistance.
ls248 is a 4-wire seven-segment decoder driver BCD input, with a pull-up resistance, 248 is a BCD seven-segment decoder/driver with an internal pull-up resistance, a total of 5474248 and 5474LS248 two line structure types.
LS48: TTL BCD - 7-segment decoding/boost output driver 74LS148: TTL eight-wire three-wire priority encoder 74LS192: TTL can be preset BCD dual-clock reversible counter 74LS2279: This chip does not seem to oh, I guess you are wrong.
LS192 is a double clock, can be preset number, asynchronous reset, decimal (BCD code) reversible counter, also can choose 54HC192, 54HCT192, 74HC192, 74HCT192 and so on.
Figure 4. Binary counter 3 composed of 74ls90. The decoding display unit 74LS248 (74LS48) is a display decoder from BCD code to seven-segment code, which can directly drive a common cathode nixie.
exclusion is not a substitute for 74ls245, the exclusion is often used for OC output as a pull-up resistance, through the pull-up resistance can get a high level. However, the 74LS245 is a two-way 8-bit drive, and an exclusion will not achieve this function in any case.
The P0 port of the 51 microcontroller is directly connected to the 74LS series chip, there is no need to add pull resistance, and naturally it can be high.
It's just a drawing, but I left it out for simplicity. ifReally want to do the real thing this is definitely not good, must be added. Another reason is that if you draw a simulation with Proteus, you can also omit the resistance, which has no effect on the simulation effect, because it is, after all, a software simulation, and it is not a physical object, which can be omitted.
This chip I have used, 74LS245 is used to drive LED or other equipment, it is 8 in phase three state bidirectional bus transceiver, can bidirectional transmission data. 74LS245 also has a bi-directional tristate function, which can output or input data.
The input low-level current is -0.2mA, the input high level current is 20uA; The output low current is 24mA and the output high current is -15mA." . The output of 20mA per port is fine. Does your stepper motor have a power supply? Without 245 direct drive is a little difficult for it, 20mA is too small for the motor.