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Aum Amriteswaryai Namah:

Aum Amriteswaryai Namah:. Serial Communication. PIN DIAGRAM. When two processors are to communicate, more often the communication is organized in a bit serial fashion. The communication may be. simplex transmission. half duplex. full duplex. Asynchronous Communication.

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Aum Amriteswaryai Namah:

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  1. Aum Amriteswaryai Namah: SerialCommunication

  2. PIN DIAGRAM • When two processors are to communicate, • more often the communication is organized in a bit serial fashion The communication may be • simplex transmission • half duplex • full duplex Asynchronous Communication Connection for simplex serial transmission between two Cs

  3. The two processors should communicate bit streams at a prearranged bit rate called ‘baud rate’ • Baud rate represents the number of bits per second at which the transmission and reception between the two processors take place Consider the implementation of a scheme at 9.6 K baud. • It implies transmission at 9600 bits per sec • each bit takes 104.25μs for transmission • both the Cs will have a clock of 104.25μs time period; it is called the ‘baud rate generator’;

  4. Asynchronous transmission of a byte at 9.6 kbaud

  5. Connection for half duplex serial transmission between two Cs

  6. Connection for full duplex serial transmission between two Cs

  7. Synchronous Communication Connection for synchronous half duplex transmission between two Cs Connection for synchronous full duplex transmission between two Cs

  8. Four Cs connected for communication amongst them in half duplex asynchronous mode Address assignments to different Cs in Figure

  9. USART and Overheads • ‘Universal Synchronous Asynchronous Receiver Transmitter (USART)’ – a module which carries out the serial communication • The simplest USART will have the following features. • A baud rate generator. • Parallel to Serial Converter: • Insertion of additional bits: • Data recovery at Receiver: • Programmability: • Bit checks: • Buffers: • Interrupts: • Error Indication:

  10. USARTin PIC16 SERIES The PIC16 series have an USART built in with a transmitter block and a receiver block within Baud Rate Generator The baud rate is derived from the processor clock by dividing it by a selected byte – X – in the 0 to 255 range. In synchronous mode In asynchronous mode or The number X is to be loaded into SPBRG register

  11. Transmitter SPEN

  12. Receiver

  13. Nine-Bit Transmission • Tx9 [TXSTA<b6>] and RX9 [RCSTA<b6>] are to be set to select the 9 bit scheme . Can be used for two purposes 1. As address/data indication bit • When the master sends out bytes, the first one can be the address. • Bit – b8 – can be set indicating that the associated byte is an address. • All slaves sense b8; if b8 = 1, they check for an address match; each can accept further bytes only if it finds an address match. • 2. As Parity bit

  14. Now..,try this out!!!!!! ? Calculate the baud rate error for the following conditions: FOSC = 16 MHz Desired Baud Rate = 9600 BRGH = 0 SYNC = 0

  15. Solution

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