Extract IC ATMEGA162P Code out from its flash memory and eeprom memory, the format of code will be heximal and the status of microcontroller will be turned from locked to unlocked one after break MCU;

Internal clock generation is used for the asynchronous and the synchronous master modes of operation. The description in this section refers to Figure 84. The USART Baud Rate Register (UBRRn) and the down-counter connected to it function as a programmable prescaler or baud rate generator if microcontroller atmega168pv code extraction.

The down-counter, running at system clock (fosc), is loaded with the UBRRn value each time the counter has counted down to zero or when the UBRRLn Register is written.

A clock is generated each time the counter reaches zero. This clock is the baud rate generator clock output (= fosc/(UBRRn+1)). The Transmitter divides the baud rate generator clock output by 2, 8 or 16 depending on mode. The baud rate generator output is used directly by the Receiver’s clock and data recovery units after IC attiny24 code extraction.

However, the recovery units use a state machine that uses 2, 8 or 16 states depending on mode set by the state of the UMSELn, U2Xn and DDR_XCKn bits.

Table 98 contains equations for calculating the baud rate (in bits per second) and for calculating the UBRRn value for each mode of operation using an internally generated clock source before mcu attiny44 code extraction.

The transfer rate can be doubled by setting the U2Xn bit in UCSRnA. Setting this bit only has effect for the asynchronous operation. Set this bit to zero when using synchronous operation.

Setting this bit will reduce the divisor of the baud rate divider from 16 to 8, effectively doubling the transfer rate for asynchronous communication. Note however that the Receiver will in this case only use half the number of samples (reduced from 16 to 8) for data sampling and clock recovery, and therefore a more accurate baud rate setting and system clock are required when this mode is used. For the Transmitter, there are no downsides.

External clocking is used by the synchronous slave modes of operation. The description in this section refers to Figure 84 for details.

External clock input from the XCKn pin is sampled by a synchronization register to minimize the chance of meta-stability. The output from the synchronization register must then pass through an edge detector before it can be used by the Transmitter and Receiver.

This process introduces a two CPU clock period delay and therefore the maximum external XCKn clock frequency is limited by the following equation:

Note that fosc depends on the stability of the system clock source. It is therefore recommended to add some margin to avoid possible loss of data due to frequency variations.

When synchronous mode is used (UMSELn = 1), the XCKn pin will be used as either clock input (Slave) or clock output (Master). The dependency between the clock edges and data sampling or data change is the same. The basic principle is that data input (on RxDn) is sampled at the opposite XCKn clock edge of the edge the data output (TxDn) is changed.