基于at89c51单片机的led显示控制系统_毕业设计外文翻译

基于at89c51单片机的led显示控制系统_毕业设计外文翻译内容摘要：

unit circuit . Serial Communication Interface Circuit D Serial Communication Interface Circuit PC and SCM are linked via a serial munication interface. In order to implement serial munication function between MCU and PC, and serial interface level of SCM will be changed into standard RS232C level [11]. Where the output voltage of PC’s RS 232C port is 177。 12V. MCU and PC, taking into account the short distance munication, and microcontroller is mainly responsible for receiving mands and data, so the PC is directly connected with the microcontroller, this is the simplest connection method. the signals which is from PC’s TXD side were changed into a current signal through the munication circuit, the infrared lightemitting diodes of optocouper have current when a signal occurs, the light signals which is emitted by diode projected onto the and phototransistor,converted to electric signal, then input to the microcontroller RXD side, so photoelectric conversion is implemented, and electrical is pletely isolated to avoid the feedback and interference which is produced by output side. as is shown in Figure 6 IV. SOFTWARE DESIGN The entire software design mainly poses of display program and munication program. The Chinese characters to be displayed on the screen,character and other data for transmission control and display functions were achieved by dynamic scan. Realtime munication parts which municate with PC receive data information by SCM serial disruption, so realtime data information transmission with PC was implemented. The host puter software was implemented by Visual Basic. In the standard serial munication, MSCOMM which is the power munication control is provided by VB, it can set the serial munication of data sent and received, and the serial munication port status, message formats and protocols are set, directly send data by PC’s RS 232/RS485 serial port. In order to realized to PC reliable munication with SCM, and ensure that both sides have the same data format and baud rate [11], this design uses RS232 munications, a 10 bits data format, 9600bit / s baud rate. A Principles of Chinese characters dot matrix display and Subcodes Chinese Times New Roman font which is UCDOS was taken as an example, each word posed of 16 16 dot matrix. That is, every word of the national standard Chinese character library expressed by the 256 can understand each point as a pixel, and the shape of each word understood as an image. In fact, this character display screen not only can display Chinese characters, but also can display any graphics within the scope of 256 pixels. Due to the bus of microcontroller is the 8bit, and a word need to split into two parts, as is shown figure 7. . Principles of Chinese characters display In order to understand Chinese characters dot matrix position law, at first, the characters code was obtained by column scanning method. Chinese characters are divided into upper part and lower part, the upper part posed of 8 16 lattice, the lower part was also formed by the 8 16 lattice. The first column of the upper left corner which was the upper part was shown by Column scanning method first, namely, P00~P07 port of 0 column, direction was P00~P07, Chinese character for large was displayed, P05 was on, the other is off. That is, binary is 00000100, and convert to hexadecimal as 04h. After the first column of the upper part was over, and continue to scan the bottom half of the first column, It can be seen from Figure 7, this column is not on all, that is, binary was 00000000, hex was 00h. According to this method, the second column, third column, until the sixteenth was scanned in turn. Characters big scan code can be drawn. 04H, 00H, 04H, 02H, 04H, 02H, 04H, 04H 04H, 08H, 04H, 30H, 05H, 0C0H, 0FEH, 00H 05H, 80H, 04H, 60H, 04H, 10H, 04H, 08H 04H, 04H, 0CH, 06H, 04H, 04H ,00H, 00H It can be seen from this principle, no matter what font or image display, we can use this method to analyze the scan code and appears on the screen. Although above methods allow us to figure out the code for character dotmatrix process, but rely on manual methods for character code is a very plicated matter. To this end, Font software is used to find the character code, the content to display is entered after the software opens, font and size can be chosen according to requirements, you can select modulo by row or by column. Press the modulus button, the hexadecimal data character code can be automatically generated, we need to copy the data into the program. B. Address Assignment the Port and Data Memory In this design, we used to 8255A, 6264 and other external devices, and their gating is not the same, so strobe is controlled, which involves the address allocation problem. In the system, the address code of 8255A is 3FFCH ~ 3FFFH and 7FFCH ~ 7FFFH, the address code of 6264 is 0A000H ~ 0BFFFH. In addition, memory 6264 is divided into four zones, each space size is 2K, the TABLE I. corresponding address code is 0A000H ~ 0A7FFH,0A800H ~ 0AFFFH, 0B000H ~。