use barcode reader in asp.net Synchronous Serial Interfaces in Software

Printer QR-Code in Software Synchronous Serial Interfaces

Synchronous Serial Interfaces
Scan QR Code JIS X 0510 In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Generating QR Code JIS X 0510 In None
Using Barcode creator for Software Control to generate, create QR Code ISO/IEC18004 image in Software applications.
For synchronous data communications in a microcontroller, a clock signal is sent along with serial data, as shown in Fig. 17.38. The clock signal strobes the data into the receiver, and the transfer can take place on the rising or falling edge of the clock. This method of transmission is different from the asynchronous protocol by the provision of the clock line from the transmitter; in asynchronous communications, the receiver is expected to provide a clock for timing the incoming data. The clock used in asynchronous transmission must be very precise and closely matched to the receiver, whereas in synchronous transmission there is only one clock, and the receiver does not need to be precisely tuned for accepting the transmitter s data.
QR Code JIS X 0510 Reader In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
Denso QR Bar Code Creator In C#
Using Barcode creator for .NET framework Control to generate, create QR Code ISO/IEC18004 image in .NET applications.
Clock Data
QR Code ISO/IEC18004 Printer In VS .NET
Using Barcode encoder for ASP.NET Control to generate, create QR Code image in ASP.NET applications.
QR Code Printer In Visual Studio .NET
Using Barcode creator for .NET framework Control to generate, create QR Code ISO/IEC18004 image in .NET framework applications.
Figure 17.38 Synchronous communications consist of data being latched into the receiver using a clock from the transmitter.
Draw QR-Code In Visual Basic .NET
Using Barcode generation for Visual Studio .NET Control to generate, create Quick Response Code image in .NET applications.
Code-39 Generator In None
Using Barcode drawer for Software Control to generate, create Code39 image in Software applications.
SYNCHRONOUS SERIAL INTERFACES
Drawing Bar Code In None
Using Barcode generator for Software Control to generate, create barcode image in Software applications.
Encoding EAN / UCC - 14 In None
Using Barcode creation for Software Control to generate, create UCC - 12 image in Software applications.
Microcontroller
Drawing EAN-13 Supplement 5 In None
Using Barcode generation for Software Control to generate, create GTIN - 13 image in Software applications.
Print Code 128 In None
Using Barcode generation for Software Control to generate, create USS Code 128 image in Software applications.
74LS374 8Q
USD - 8 Encoder In None
Using Barcode drawer for Software Control to generate, create Code 11 image in Software applications.
1D Drawer In Java
Using Barcode generator for Java Control to generate, create Linear Barcode image in Java applications.
74LS374 8D 8Q
Painting Data Matrix ECC200 In None
Using Barcode encoder for Word Control to generate, create DataMatrix image in Microsoft Word applications.
Read Data Matrix In Visual Studio .NET
Using Barcode recognizer for .NET Control to read, scan read, scan image in VS .NET applications.
4D 3Q 3D 2D 1D OE 3Q 2Q 1Q 3D 2Q 1D OE 2D 1Q
Barcode Encoder In Java
Using Barcode creation for Java Control to generate, create bar code image in Java applications.
Printing Data Matrix ECC200 In .NET
Using Barcode creation for VS .NET Control to generate, create Data Matrix ECC200 image in VS .NET applications.
Clock Data O/P Clock
Drawing Barcode In None
Using Barcode generation for Font Control to generate, create barcode image in Font applications.
EAN / UCC - 14 Encoder In None
Using Barcode drawer for Excel Control to generate, create GTIN - 128 image in Microsoft Excel applications.
Figure 17.39 Converting synchronous serial data to parallel bits is quite easy to do.
A typical circuit using discrete devices could be that in Fig. 17.39. This circuit converts serial data into eight digital outputs that all are available at the same time (when the O/P clock is strobed). For most applications, the second 374 providing the parallel data is not required. This serial-to-parallel conversion also can be accomplished using serial-to-parallel chips, but I prefer using 8-bit registers because they are generally easier to nd than other TTL parts. There are two very common synchronous data protocols Microwire and SPI. These methods of interfacing are used in a number of chips (such as the serial EEPROMs used in the BASIC Stamps). While the Microwire and SPI standards are quite similar, there are a number of differences that should be noted. I consider these protocols to be methods of transferring synchronous serial data rather than microcontroller network protocols because each device is addressed individually (even though the clock/data lines can be common between multiple devices). If the chip select for the device is not asserted, the device ignores the clock and data lines. With these protocols, only a single master can be on the bus. If a synchronous serial port is built into the microcontroller, the data transmit circuitry might look like that in Fig. 17.40. This circuit will shift out 8 bits of data. For protocols such as Microwire, where a start bit is sent initially, the start bit is sent using direct reads and writes to the I/O pins. To receive data, a similar circuit would be used, but data would be shifted into the shift register and then read by the microcontroller. The Microwire protocol is capable of transferring data at up to one megabit per second. Sixteen bits are only transferred at a time. After selecting a chip and sending a start bit, the clock strobes out an 8-bit command byte (labeled OP1, OP2, A5 to A0 in the diagram above), followed by (optionally) a 16-bit address word transmitted and then another 16-bit word either written or read by the microcontroller. The SPI protocol is similar to Microwire, but with a few differences:
1 SPI is capable of up to 3 Mbps data transfer rate. 2 The SPI data word size is 8 bits.
PIC MCU INPUT AND OUTPUT DEVICE INTERFACING
Timer PWM Output 1 8 Cntr Shift Register
Start
Data Sent Signal
MCU Data Bus
Figure 17.40 The synchronous serial hardware built into the PIC microcontroller allows data to ow through the input and output pins.
3 SPI has a hold that allows the transmitter to suspend data transfer. 4 Data in SPI can be transferred as multiple bytes known as blocks or pages.
Like Microwire, SPI rst sends a byte instruction to the receiving device. After the byte is sent, a 16-bit address is optionally sent, followed by 8 bits of I/O. As noted earlier, SPI does allow for multiple-byte transfers. An SPI data transfer is shown in Fig. 17.41. The SPI clock is symmetric (an equal low and high time). Output data should be available at least 30 ns before the clock line goes high and read 30 ns before the falling edge of the clock. When wiring up a Microwire or SPI device, there is one trick that you can do to simplify the microcontroller connection, and that is to combine the DI and DO lines into one pin. Figure 17.42 is identical to what was shown earlier in this chapter when interfacing the PIC microcontroller into a circuit where there is another driver. In this method of connecting the two devices, when the data pin on the microcontroller has completed sending the serial data, the output driver can be turned off, and the microcontroller can read the data coming from the device. The current-limiting resistor between the data pin
Copyright © OnBarcode.com . All rights reserved.