What is TTL level, CMOS level, RS232 level? What difference do they have? Generally, the CMOS level has a higher noise tolerance than the TTL level.(i), TTL level standard output L: (ii), CMOS level standard output L: (c), RS232 standard logic 1 level of -3~-15v, logic 0 level of +3~+15v, pay attention to the definition of the level is reversed once.What is the difference between TTL and CMOS level 1. The u
Reproduced on: RS232, RS485 Waveform Analysis
I often encounter problems with single-chip serial communication for beginners and do not know how to do it. In fact, the most effective debugging method is to use an oscilloscope to observe the waveforms of the sent and received data. Observe the waveform to determine the following situations:
Whether data is received or sent
Is the Data correct?
Whether the baud rate is correct
1. Serial Data Format
1 logic level
EIA-RS-232C of electrical properties, logic and various signal line functions are defined.
On txd and rxd:
Logic 1 (Mark) =-3v ~ -15 V
Logic 0 (Space) = + 3 ~ + 15 V
On the control line such as RTS, CTS, DSR, DTR, and DCD:
Effective Signal (on, positive voltage) = + 3v ~ + 15 V
Invalid signal (disconnected, off, negative voltage) =-3v ~ -15 V
2. Pin Definition
Pin definition symbol
1 Carrier Detection DCD Pin 1 received Line Signal Detector (data carrier dete
This tool is USB1.1, relatively old, a start to do little white mouse do not know to buy USB1.1, so I do not recommend to buy this, there are other models, support USB2.0 and USB3.0, but the price is relatively expensive, this is only about 30 yuan.Key Force special Use PL2303 chip, compatibility is very good, widnows 7+, Linux, Mac 10.9+ can support.Comparison is the driver download, official web download driver for ze398c is not used, can only drive the contents of the CD to install, and this
Long time no use of hardware, the serial port is long useless use.Once the interface signal remember very clearly, long, forget.Today, re-review, note notes.The DB9 interface is divided into male head and female head, male plug needle, computer chassis how many male head. The female head is the jack socket.Reasonable hardware design is the male head of the computer for reference, its 2 for the collection, 3 for the hair, 5 for the ground, Memory: male 235 transceiver .OK, bye.(original)
Receive SMSThere are two ways to receive incoming SMS: polling terminal; using eventspolling terminals can be used on a regular basis The at+cmgl=0 instruction reads the unread fetch instruction. The method is simple, but many times do not work hard, inefficient, generally not recommended. The following is the main explanation of event law:Instructions:At+cnmi=Parameters:Mode:0--cache in terminal1--Send directly to TEMt:0--Receive new SMS does not return event1--if the received SMS is stored in
I used 232 of the communication protocols. I forgot to use Google every time I used them. Write an articleArticle, Record key issues of the 232 serial port protocol for later viewing.
Test TTL level:
1. The default high level;
2. the start position is low;
3. 8-Bit Data bit,Low front, high behind;
4. The stop bit is high.
Test RS232 level:
1.-5v---15v is 1, negative logic;
2. Convert the TTL to the 232 chip and convert the high level to
Ubuntu comes with most USB to RS232 drives, all we have to do is find the device name that corresponds to the device.
Enter LSUSB under the terminal to list the USB devices identified by the system
$ LsusbBus 008 Device 001:id 1d6b:0002 Linux Foundation 2.0 root HubBus 003 Device 002:id 064e:a103 suyin Corp.Bus 003 Device 001:id 1d6b:0002 Linux Foundation 2.0 root HubBus 007 Device 001:id 1d6b:0001 Linux Foundation 1.1 root HubBus 006 Device 001:id 1
Design the simplest RS232 communication logic, the FPGA implementation will receive the data will be sent out, a total of two data transmission pins, a receive. Divide this communication module into three parts:
1. Baud Rate Control Module
2, send the module.
3. Receiving module
Here is the Code section:
Module Baud_counter (//Inputs input CLK, input reset, input reset_counters,//Outputs output reg baud_clock_rising_e
Dge, output reg Baud_clock_fa
Both RS232 and RS422 are widely used asynchronous serial interface standards. Because they are simple to implement and consume less resources in IO ports, it is a good idea to transfer at low speed.The RS232 is a single-ended route with a maximum baud rate of 115200 and a transmission distance of no more than 150 meters, with a logic 1 level of 3 to -15v and a logic 0 level of 3 to 15V.The RS422 is a differ
Maxcompute is a chip that converts the rs232 signal level (-10, + 10 v) of a computer serial port to the TTL signal point (0, + 5) used by a single-chip microcomputer, the price of this chip is about 6 yuan. Next I will introduce the maxcompute pin diagram, the connection circuit between maxcompute and the computer serial port, and the RS232 pin definition. ************************ * ** Maxcompute chip is t
Differences Between RS232 and RS485
1. RS-232-C is a serial physical interface standard developed by the American Association of Electronic Industry EIA (Electronic Industry Association. RS is the abbreviation of the English "Recommendation Standard". 232 indicates the ID number, and C indicates the number of modifications. RS-232-C bus standard has 25 signal lines, including a main channel and a secondary channel, in most cases the main channel,
.
Differential operation is the root cause of long transmission distance at the same rate, which is the fundamental difference between the two and RS232. Because RS232 is a single-ended input and output, at least the digital ground line is required for duplex operation.. Transmission Line and receiving line (asynchronous transmission). You can also add other control lines to complete synchronization and oth
Both VGA and DVI are video transmission lines. The former is the traditional analog transmission, the latter species is more, there is only the transmission of digital or analog or digital mode is transmitted, in short, the latter video signal transmission quality is higher than the former, and transmission speed faster. Many displays on the market now use the DVI interface (including HDMI, HDTV, and DisplayPort, etc.)Interfaces are very easy to differentiate:
What are the differences between VGA, DVI, RS232, UART, SCSI, SATA, and other interfaces?Both VGA and DVI are video transmission lines. The former is a traditional analog transmission, and the latter has many types, which only transmits numbers or analog or digital models. In short, the latter's video signal transmission quality is higher than the former, and the transmission speed is faster. At present, many monitors on the market use DVI interfaces
RS232 serial communication principle
The serial port is a protocol used to communicate with a very general device on a computer (do not confuse it with the Universal Serial Bus or USB ). Most computers contain two RS232-based serial ports. Serial Port is also a universal communication protocol for instrumentation equipment; many devices are also compatible with the RS-232 port. At the same time, the serial
convenient for testing)ATE183. Check and set character sets:At+cscs=?8+cscs: ("GSM", "UCS2")indicates that the terminal supports GSM and UCS2 two kinds of character sets. General for Chinese environment set to UCS2At+cscs= "UCS2" 84. Get SMS Center number:At+csca? 8+csca: "+8613800280500", 1455. Query and set the SMS format:Enquiry: At+cmgf= 8return:+CMGF: (0)0 represents the PDU mode. Your device may have additional options, please refer to the device's at instruction set. Settings: at+cmgf=08
Query SMS:1 . Query all text messages with the same statusdirective: At+cmgl=nwhere n represents the number of 0-4. 0--unread text messages. Executes the command and then changes itself to read. 1--read SMS. 2--Draft. 3--SMS has been sent. 4--AllReturn (example):+cmgl:76,3,,200891683108200805f011620d91683194041338f50000ff0530972d8603--Serial number3--Status: Send--PDU string length2, query the specific serial number of SMSdirective: At+cmgr=n8where n represents the ordinalReturn (example):+cmgr:
* COM is displayed in the PC adapter that sets the pg/PC interface in Step 7. Indicates that the comport is replaced by another
ProgramOccupied. When kepserverex4.0 is used, when the Siemens S7 MPI device driver is used, the COM1 port is prompted
What is a RS-232-C interface? What are the characteristics of the use of RS-232-C interface? How to consider the length of the transmission cable?
A: data transmission between a computer and a computer or between a computer and a terminal can be
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