“The main controller MSP430F413 microcontroller is an ultra-low power mixed-signal 16-bit microcontroller series, using a 16-bit simplified instruction system, 125 ns instruction cycle, most of the instructions are completed in one instruction cycle, 16-bit registers and constant generator, play The highest code efficiency, and the chip contains a hardware multiplier, which greatly saves computing time. The MSP430F413 single-chip microcomputer is selected, and the online system design, development, debugging and practical application all show obvious advantages compared with other single-chip microcomputers.
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1 Introduction
Electronic paper (ePaper) is a new generation of Display devices with ultra-high contrast, ultra-low power consumption, ultra-thin, and can be bent and folded at will, with good flexibility. The MSP430 series single-chip microcomputer is a 16-bit ultra-low power mixed signal processor (Mixed Signal Processor) that Texas Instruments (TI) began to market in 1996. It is called a mixed-signal processor, mainly because it integrates many analog circuits, digital circuits and microprocessors on a single chip to provide a “single-chip” solution for actual application requirements. This article introduces the hardware driver and design of the electronic paper of the new generation display device, introduces the main functions of the main controller MSP430 microprocessor, and realizes the low power consumption of the electronic paper drive configuration. The corresponding function subroutines of the electronic paper display module are given. Use its built-in LCDRAM as the display buffer, I/O simulation timing, make full use of MCU resources and improve the portability of the program. Complete the design of the MSP430-based electronic paper drive interface.
2 Electronic paper hardware design
The main controller MSP430F413 microcontroller is an ultra-low power mixed-signal 16-bit microcontroller series, using a 16-bit simplified instruction system, 125 ns instruction cycle, most of the instructions are completed in one instruction cycle, 16-bit registers and constant generator, play The highest code efficiency, and the chip contains a hardware multiplier, which greatly saves computing time. The MSP430F413 single-chip microcomputer is selected, and the online system design, development, debugging and practical application all show obvious advantages compared with other single-chip microcomputers.
This design uses E-INK company segment code electronic paper, as shown in Figure 1. Electronic paper is a colored ball with static electricity sandwiched between two layers of transparent film. The particles of two colors are charged with positive and negative static electricity. Positive and negative electrodes are placed on the outside of the film to repel the same sex and attract the opposite sex. Bright a certain section, Figure 2 is a cross-sectional view of the electronic ink microcapsule. The electronic paper truth table is similar to the static display liquid crystal module, divided into SEG segment and TopPlane segment. When there is a potential difference between the SEG segment and the TopPlane segment, the electronic ink in the electronic paper will move, and the corresponding segment will light up and go out.
Figure 3 is the system hardware connection diagram. The electronic paper needs a special driver to drive the display. The electronic paper drive device of this design adopts the S1C05112, S1C05112 built-in interface circuit and drive electronic paper module produced by EPSON. It adopts 3 V power supply, which is convenient for communication. MCU communication. The electronic paper drive module is respectively connected with the I/O port of the MCU. Simulate the timing diagram of the electronic paper drive module through I/O.
3 software design
The software part adopts a modular design idea to simplify the program, which is convenient for the design, debugging and maintenance of the program. The macro definition is adopted in the program design, which is convenient for program transplantation. Nanyu’s electronic paper must be refreshed every time it displays, occupying most of the controller’s memory resources, so the design makes effective use of its LCD RAM.
3.1 E-paper driver initialization
The initialization content includes electronic paper DC-DC converter settings, chip select enable and clock signal input, to make full preparations for display refresh. Figure 4 is a communication timing diagram. The power-on sequence is LO_ACT. XCS, DD_ACT.
3.2 Refresh the display electronic paper
This function reads the data in LCDRAM, by querying the data in LCDRAM and then sending it directly to the I/O port, the electronic paper drive device refreshes the electronic paper after obtaining the display data. The related program code is as follows:
3.3 Low-power design
By configuring the power module of the electronic paper drive to minimize its power consumption, that is, pull down the configuration bits DD_ACT and LO_ACT of the electronic paper drive, and the electronic paper drive device is in a standby state. At this time, the electronic paper can still display, including when the power is off.
4 Power consumption analysis
Table 1 is the power consumption analysis of the entire interface. The MCU and S1C05112 are divided into working and standby states for analysis.
It can be seen from Table 1 that the total standby current of the entire interface is only 0.2μA, and it is only 240μA in the computing state. In actual applications, the display refresh frequency is not the same. 240μA is the limit state of the system.
With the development of modern electronic technology, the application of electronic paper has rapidly expanded, and it is used in supermarket price tags, in mobile phones, and e-book readers. Electronic paper has become a new display technology used in portable electronic devices after liquid crystal and OLED.
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