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74HC164 Based Display Drive Circuit Design

Author: Iggy
Date: 14 Oct 2020
 751
74hc164 circuit diagram

I. Description

Nowadays, LCD, VFD, LED and other display devices have brought infinite charm to intelligent household appliances. At present, major chip manufacturers have introduced various dedicated display driver chips,  they have become the mainstream of display drive technology. However, the display requirements of white goods are relatively low. Based on cost considerations, this article introduces a 74HC164-based display drive circuit design scheme, which not only achieves the same display effect, reduces costs, but also improves system reliability.

74HC16474HC164

Catalog

I. Description

II.74HC164 Advantage Analysis

III.74HC164 Chip Introduction

IV.74HC164 Display Drive Circuit

V. 74HC164 Display Circuit Driver

VI. Procedure Description

FAQ

Ordering & Quantity

 

II.74HC164 Advantage Analysis

 

Under normal circumstances, the display circuit of smart home appliances is controlled by a single-chip microcomputer, such as the displayed content and the display mode. The single-chip microcomputer plays an important role in the control circuit of smart home appliances. Its selection not only determines the realization of the control circuit, but also has a great influence on the cost of the controller.

 

We use the serial input and parallel output functions of the 74HC164 chip to carry out serial communication with the microcontroller, and the parallel output port directly drives the display device. This solution can expand the I/O port of the single-chip microcomputer and reduce the resource requirements of the single-chip microcomputer. Moreover, the chip installation method is very flexible, which can reduce the number of connecting wires of the display panel, improve the reliability of the system, and has a greater cost advantage. , It is widely used in buttons and display drive circuits.  

 

III.74HC164 Chip Introduction

 

74HC164 is a high-speed silicon gate CMOS device, which is pin compatible with low-power Schottky TTL (LSTTL) devices. 74HC164 is an 8-bit edge-triggered shift register, serial input data, and then parallel output. Data is serially input through one of the two input terminals (DSA or DSB); either input terminal can be used as a high-level enable terminal to control the data input of the other input terminal. Either connect the two input terminals together, or connect the unused input terminals to a high level, so they must not be left floating. The pin distribution of 74HC164 is shown as in Fig. 1. Compatible with TTL level, the highest operating clock frequency is 20MHz, the fan-out factor is 10, the power dissipation is 500mW, and the output current Io (each end) is 25mA, which can directly drive LED display devices.

Figure 1 74hc164 pinout

Figure 1 74hc164 pinout

According to the logic function of the chip, the waveform diagram of the input and output signals can be obtained, as shown in Figure 2. The output signals Q0~Q7 are delayed by one clock cycle respectively, and can form 8 scan signals.

Figure 2 74HC164 signal waveform

Figure 2 74HC164 signal waveform

 

IV.74HC164 Display Drive Circuit

 

The circuit shown in Figure 3 is a hybrid display circuit composed of touch switches, nixie tubes and LEDs. Among them, 16 buttons, 2 nixie tubes, and 8 LEDs are a typical 538 scanning circuit. The 8 pins of the 74HC164 chip Q0~Q7 output column scan signals, and the microcontroller directly provides 5 rows of scan signals. The single-chip microcomputer provides clock input and data input signals for 74HC164 to control the display content. The circuit requires 8 pins of the single-chip microcomputer in total, which saves 6 pin resources compared with the conventional scanning circuit and has certain cost advantages.

 

Diode D2-D23 plays an isolation role to prevent the mutual interference of 74HC164 chip pin potential. For example: when a channel is selected, the 74HC164 output pins Q0~Q6 are high level, and Q7 is low level. At this time, if SW1 and SW2 are pressed at the same time, pin Q7 and pin Q6 are in a short-circuit state, which will damage the chip.

 

Clock input pins and data input pins need to be connected to ceramic capacitors to resist high-frequency interference, but the capacitance should not be too large to avoid excessive distortion of the input waveform and make the circuit unable to work normally. It is recommended to use 100-1000pF.

Figure 3 shows a practical example of the circuit

Figure 3 shows a practical example of the circuit

 

V. 74HC164 Display Circuit Driver

 

Take the 78K0S series 8-bit MCU UPD78F9116 from NEC Corporation of Japan as an example, the driver needs to detect 16, the number of keys to be detected, the display drive 2 8-segment digital tubes, and the number of LEDs 16 (8 expanded on the basis of the reference circuit). The single-chip microcomputer directly provides 6 line scan signals, and at the same time provides clock input and data input signals for 74HC164 to control the display content. The IO port is defined as follows:

Each subroutine scans 2 groups of 31 keys, and scans all keys within 8 times. Display scan channel number 0~3, display time of each channel (1 digital tube or 1 group of LED) occupies 1/4, and the refresh cycle depends on the frequency of subroutine execution. The program must be executed cyclically. It can be called as a regular subroutine or directly embedded in the main program file. It is more appropriate to execute it every 1~3mS. The confirmation time for a button to be lifted or pressed (24mS~32mS)--(72ms~96mS), the response speed can meet people's operating habits, the display refresh frequency is set to 250Hz--83Hz, if it is lower than 40~50Hz Flashing. The program flow chart is shown in Figure 4.

Figure 4 Program flow chart

Figure 4 Program flow chart

 

VI. Procedure Description

 

(1) External name and global variable declaration


FAQ

  • How does the 74HC164 transmit data in the microcontroller circuit?

  1. One pin of the single-chip microcomputer is like a faucet, and the data is sent one by one, that is, like the water from the faucet, dripping drop by drop. The 74H164 is like a small bowl receiving water. It is just full after receiving 8 drops of water. At this time, it is sent to the digital tube.
  2. The single-chip microcomputer must send an 8-bit (or more) data, if it is sent at the same time, it is a parallel transmission, if it is a bit by bit, it is a serial transmission. The data of the single-chip microcomputer is sent to the 74HC164 bit by bit, which is serial, and the 74HC164 sends the data to the digital tube at once, which is parallel. So 74HC164 plays a role from serial transmissionto paralleltransmission.
  • What is the difference between 74HC164D and 74HC164N MCU?

The D in 74HC164D represents a chip package. The N in 74HC164N means dual in-line plastic packaging.

  • What is the difference between 74HC164 and 74LS164, can they be used together?

74ls164 is a TTL circuit, the power supply voltage is 5V, the high-level output current Ioh is -0.4MA, and the low-level output current is 8MA.

74HC164 is a CMOS circuit, the power supply voltage is 2V ~ 6V, the output drive current can reach plus or minus 20MA. If the power supply voltage you use is 5V and the output drive current is suitable for 74ls164, they can be used together.

  • What devices can 74hc164 be replaced with?

74HC164 is a CMOS device with a power supply voltage of 2V-6V. It can be directly replaced by 74HCT164, 40H164. If the power supply voltage is 5V and the output drive current is small, it can also be replaced by 74164, 74LS164, 74F164, 74ALS164.

  • Which of 74LS164 and 74HC164 has higher driving capability?

74LS164 is a TTL device with a high-level driving capability of about 0.4mA and a low-level driving capability of about 8mA. 74HC164 is a CMOS device, with high-level and low-level drive capability up to 20mA. The above data comes from DATASHEET. But generally speaking, the high-level output capability of many CMOS devices is weak, smaller than TTL, and the low-level drive capability is stronger.

  • Can 74hc164n be used to drive the digital tube?

Of course, you can use the 164 chip to drive the nixie tube, which is mostly used in situations where the IO port resources are tight and the display data refresh of the nixie tube is slow. When designing the circuit, multiple 164 chips are used in cascade, no matter how many digital tubes are driven, only 2 IO ports of the single-chip microcomputer are occupied. It can be said that it is the most IO port-saving driving method, and it is still driven statically, without strobe and brightness Low phenomenon.

The disadvantage is that multiple 164s are used in cascade connection, which will cause the single-chip microcomputer to send a large amount of display data (1 byte per nixie tube) at one time when refreshing the display data. During this process, the nixie tube will be all on, although the data is sent The process duration is very short, but it still affects the display effect. It is recommended to turn off the digital tube when refreshing the data.

Ordering & Quality

Photo Mfr. Part # Company Description Package PDF Qty Pricing
(USD)
74HC164DB-118 74HC164DB-118 Company:NXP USA Inc. Remark:Shift Shift Register 1 Element 8 Bit 14-SSOP Package:14-SSOP (0.209"", 5.30mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
996+: $0.25116
Inquiry
74HC164N-652 74HC164N-652 Company:NXP USA Inc. Remark:IC 8BIT SHIFT REGISTER 14-DIP Package:14-DIP (0.300", 7.62mm)
DataSheet
In Stock:On Order
Inquiry
Price:
Call
Inquiry
74HC164PW 74HC164PW Company:Nexperia USA Inc. Remark:Shift Element Bit Package:N/A
DataSheet
In Stock:On Order
Inquiry
Price:
3086+: $0.08102
Inquiry
74HC164PW-112 74HC164PW-112 Company:Nexperia USA Inc. Remark:Shift Shift Register 1 Element 8 Bit 14-TSSOP Package:14-TSSOP (0.173"", 4.40mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
1+: $0.40000
10+: $0.34100
25+: $0.31840
100+: $0.25480
250+: $0.23660
500+: $0.20020
1000+: $0.15470
2500+: $0.14105
5000+: $0.13195
Inquiry
74HC164PW-118 74HC164PW-118 Company:Nexperia USA Inc. Remark:Shift Shift Register 1 Element 8 Bit 14-TSSOP Package:14-TSSOP (0.173"", 4.40mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
1+: $0.35000
10+: $0.28500
25+: $0.26040
100+: $0.19390
250+: $0.17568
500+: $0.14540
1000+: $0.10904
2500+: $0.09982
5000+: $0.09378
12500+: $0.08772
25000+: $0.08047
62500+: $0.07744
Inquiry
74HC164PW-Q100J 74HC164PW-Q100J Company:NXP USA Inc. Remark:Shift Shift Register 1 Element 8 Bit 14-TSSOP Package:14-TSSOP (0.173"", 4.40mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
1183+: $0.08102
Inquiry
CD74HC164E CD74HC164E Company:Texas Instruments Remark:Shift Shift Register 1 Element 8 Bit 14-PDIP Package:14-DIP (0.300"", 7.62mm)
DataSheet
In Stock:On Order
Inquiry
Price:
1+: $0.68000
10+: $0.60100
25+: $0.56440
100+: $0.46050
250+: $0.42772
500+: $0.36400
1000+: $0.29120
2500+: $0.26390
5000+: $0.24570
Inquiry
CD74HC164M96 CD74HC164M96 Company:Texas Instruments Remark:Shift Shift Register 1 Element 8 Bit 14-SOIC Package:14-SOIC (0.154"", 3.90mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
1+: $0.62000
10+: $0.54500
25+: $0.51160
100+: $0.41750
250+: $0.38776
500+: $0.33000
1000+: $0.26400
2500+: $0.23925
5000+: $0.22275
10000+: $0.21450
25000+: $0.20625
62500+: $0.20295
100000+: $0.19800
Inquiry
MC74HC164ADR2G MC74HC164ADR2G Company:ON Semiconductor Remark:Shift Shift Register 1 Element 8 Bit 14-SOIC Package:14-SOIC (0.154"", 3.90mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
1+: $0.45000
10+: $0.34000
25+: $0.30680
100+: $0.21200
250+: $0.17856
500+: $0.14508
1000+: $0.11160
2500+: $0.10044
5000+: $0.09486
12500+: $0.08649
25000+: $0.08091
62500+: $0.07533
Inquiry
MC74HC164ADTR2G MC74HC164ADTR2G Company:ON Semiconductor Remark:Shift Shift Register 1 Element 8 Bit 14-TSSOP Package:14-TSSOP (0.173"", 4.40mm Width)
DataSheet
In Stock:On Order
Inquiry
Price:
1+: $0.38000
10+: $0.30600
25+: $0.28040
100+: $0.20860
250+: $0.18908
500+: $0.15648
1000+: $0.11736
2500+: $0.10758
5000+: $0.10106
12500+: $0.09454
25000+: $0.08802
Inquiry

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