The MAX6955 is an LED display driver with an I2C â„¢ -compaTIble, serial interface capable of supporTIng Fast Mode speeds up to 400kHz. It is capable of driving sixteen 7-segment, eight 14-segment, eight 16-segment or 128 separate LEDs. This applicaTIon note describes a 14-segment application circuit and an example program that continuously scrolls the message:
"THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG".
The program, shown in Listing 1, can be modified to scroll alphanumeric messages with a length of 8 to 126 characters. The application circuit shown in Figure 1 consists of the MAX6955, the PIC18F442 and four super bright red 14-segment dual character displays from Lumex (Part number LDD-F5406RI).
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Figure 1. MAX6955 application schematic.
The example assembly program continuously scrolls the alphanumeric characters located in the lookup table of the program. The alphanumeric message length is adjustable from 8 to 126 characters long including all blank spaces (0x20). It is recommended to add 7 blank spaces at the beginning and end of the message to obtain the best scrolling effect. In order to customize the message, first modify the hexadecimal representation of the character to scroll in the lookup table of the program. Then modify the CharCount variable value to the number of alphanumeric characters in the selected message including all blank spaces. The program calculates the correct shift count using the equation:
CharCount-7 = ShiftCountPlusOne
ShiftCount = ShiftCountPlusOne-1
For example, "THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG" contains 43 characters. Adding 7 blank spaces before and after the message increases the character count to 57. Using the equation above shows that a message with a character count of 57 would be shifted a total of 49 segments from right to left.
The example program also contains function calls to interface the MAX6955 to the PIC using the internal MSSP I2C port. Since other microcontrollers have similar on-chip peripherals, the example I2C communication routines provided were purposely broken down into single I2C function calls so that the code can be quickly implemented with other microcontrollers. Table 1 shows the single I2C compatible function calls used in the example assembly program.
alt-click (PC) or option-click (Mac) to download Listing 1.
Listing 1. An example assembly program that interfaces the MAX6955 to the PIC18F442's internal MSSP I2C peripheral.
Table 1. Single I2C compatible function calls.
| Single I2C compatible function calls | Description |
| HWI2C_start | Performs an I2C compatible start condition. |
| HWI2C_repeatedStart | Performs an I2C compatible repeated start condition. |
| HWI2C_W_write | Performs all I2C compatible write operations including the initial slave address write frame. |
| HWI2C_readMore_W | Performs an I2C compatible read operation with Master ACK. |
| HWI2C_readLast_W | Performs an I2C compatible read operation with Master NACK. |
| HWI2C_stop | Performs an I2C compatible stop condition. |
What is an industrial router? Which industries are they mainly used in?
With the continuous development of the network and the continuous progress of various industries, some new concepts and development directions have actually emerged during the period. For example, from the current point of view, many enterprises in the development process in order to have good efficiency and speed, as well as the use of more functions, gradually began to use industrial routers. Of course, for this type of router, we also have a lot of problems, so today we will discuss to see, what is an industrial router? Which industries are they mainly used in?
What is an industrial router?
From the basic concept, an industrial router is a wireless data transmission function that provides users with wireless data transmission through a public wireless network. For example, we use mobile phone data to transfer things to another mobile phone or computer, in fact, the principle is very simple. Of course, the specific usage operation is different. In the process of use, the industrial router has the advantage of allowing multiple users to use the same integrated network system to access the network, which is also very convenient in the work. In fact, at present, industrial routers are gradually widely used in different industries, and the practicability is also very strong.
Industrial routers are mainly used in what industries?
The first is some of the contents summarized for the concept and basic principles of industrial routers, and for the use of industrial routers, it is also some of the issues that we are concerned about. From the current point of view, the first is widely used in intelligent transportation, such as in the application of high-definition electronic bayonet, road wireless video surveillance, vehicle monitoring or security monitoring, etc., which is also very important; Secondly, it is also widely used in the financial industry, such as the use of wireless atm self-service terminals, wireless pos machines or other applications; In addition, it is the application of the power industry, such as transformer remote monitoring management, circuit line video surveillance and substation video surveillance and so on. In short, the use of industrial routers is also more extensive.
How to choose an industrial router?
Although the industrial router is widely used now, the choice we made at the beginning is still more tangled, from the feedback of the market, Movingcomm router is actually very good. According to the needs of the industry environment, based on SD-WAN+ Internet of Things, intelligent networking can then be formed into a large local area network through the cloud platform router in many places. Therefore, the focus of security monitoring can also be concentrated to complete the work of remote video surveillance, but also to meet the needs of remote working, for some of the industries we mentioned earlier, the practicality of this program is also very good. Moreover, the technology of remote networking and intelligent networking is also very mature, and the security and stability are also good. In short, the advantages of Movingcomm router are still many.
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