Vhdl Code For Serial Data Transmitter Equipment
UART Communication with UART Stands for Universal Asynchronous Transmitter Receiver. The function of UART is conversion parallel data (8 bit) to serial data.
UART transmit bytes of data sequentially one bit at a time from source and receive the byte of data at the destination by decoding sequential data with control bits. As the entire processes require no clock input from source hence it is termed as asynchronous communication. Baud Rate In the UART communication data transmission speed is measured by Baud Rate.
Baud rate describes the total number of bit sent through serial communication. It includes Start bit, Data byte, Parity bit and Stop bit. Transmitter and receiver need to be maintained in the baud rate. For example transmit data at the baud rate of 9600 and at the receiving end PC need to be set with same baud rate using HyperTerminal or TeraTerminal. Packet of Data in Serial Communication Start Data 0 Data 1 Data 2 Data 3 Data 4 Data 5 Data 6 Data 7 Parity Stop Serial Communication consist of 2 lines Transmitter and Receiver pin.
Fig 1:Connection between FPGA and PC Serial data communicate on FPGA side range in 0 to 3.3v. Logic 0 is represented by 0v.
Biswa Ranjan Mundari
VHDL can be used for the behavioral level design implementation of a digital UART and it offers several advantages. The advantages of using VHDL to implement UART: VHDL allows us to describe the function of the transmitter in a more behavioral manner, rather than focus on its actual implementation at. In this lab we will design a simplified UART (Universal Asynchronous Reciever Transmitter) in VHDL and download it to the FPGA on the XS40 baord. Serial communication is often used either to control or to receive data from an embedded microprocessor. Download: Simple UART Transmitter.vhd (Right-click and select Save Link As.) Here is VHDL code for a very simple / minimalistic UART transmitter. This transmitter will output a RS-232 formatted signal with 1 START bit, 8 DATA bits and 1 STOP bit. It has been successfully tested at speeds of 300, 9600, 115200, 921600 baud.
Logic 1 is represented by 3.3v Fig 2: Voltage level of FPGA On PC Side RS232 Port voltage range from -15v to +15v. Logic 0 is represented by +3v to 15v. Logic 1 is represented by -3v to -15v Fig 3: Voltage level of PC In order to communicate between FPGA and PC with different voltage level, MAX3232 Driver IC is required. It consists of 2 channel transmitter and Receiver. Serial communication The data communication of UART is made by 11 bit blocks.
Fig 4: Serial communication The wave form showed the protocol of the UART. Here the ‘0’ bit represent as start bit which is initiated the serial communication. The start bit must be ‘0’. The next 8 bit’s are data bit. The LSB bit of data goes as first bit continue it sent other 7 bits. The 10 th bit is a parity bit which is used to identify error in the communication. The parity bit is either 0 or 1 which is depending on the number of 1’s present in transmission.
If even parity is used, the number of bit must be even. If odd parity is used, the number of bit must be odd. The speed of transmission is fixed which is measured by baud rate. The last bit is stop bit which must be ‘1’. Note: The parity bit is not necessary which is optional. Transmission delay The transmission rate is measured by bits per second. Each bit has a fixed time duration while transmission.
The transmission delay for each bit 104.16 μs which is constant till the end of communication. Example The baud rate is 9600. Transmission delay =1/9600 =104.16 μs.
RS 232 connector and cable RS 232 connector is used to establish connection between and PC. It is either male or female connector.
Here we use only female to female connector. RS 232 connector has only 9 pins, even though the only 3 pins are enough to make a transmission between PC and FPGA such as RD,TD and GND Fig 5:RS232 connector Table 1: Pin Signal 1 2 Received data(RD) 3 Transmitted data(TD) 4 Data terminal ready(DTR) 5 Signal ground(GND) 6 Data set ready(DSR) 7 Request to send(RS) 8 Clear to send(CS) 9 Ring indicator(RI) RS232 interface using Max3232 Driver IC with Fig 6: Schematic diagram of FPGA and MAX 3232 UART Placement in In this article, 3 example codes are provided to demonstrate the UART Communication. 1 st VHDL Code describes Transmitting data from PC HyperTerminal to and feedback to PC at 9600 Baud Rate. This Code consists of Clock and Reset input. Clock running at 50MHz and Reset is assigned to Slide switch to enable or disable Serial Communication. Din and Do are transmit and receive of the FPGA. The Functionality of this code can be explained by 2 process statements.
Vhdl Code For Serial Data Transmitter Equipment Free
Process 1 involves transmission of data from PC to FPGA and stores them in array. Process 2 involves retransmission of data stores in FPGA array to PC.