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What is the significance of baud rate in UART?
The baud rate is the rate at which information is transferred in a communication channel. Baud rate is commonly used when discussing electronics that use serial communication. In the serial port context, “9600 baud” means that the serial port is capable of transferring a maximum of 9600 bits per second.
How fast can a UART run?
UART interfaces have a maximum data rate of around 5 Mbps. There is also some protocol overhead in the form of start, stop, and parity bits. The data rate of a UART interface is similar to that of an I2C interface.
What is the default baud rate?
Standard baud rates include 110, 300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 38400, 57600, 115200, 128000 and 256000 bits per second. To display the supported baud rates for the serial ports on your platform, refer to Finding Serial Port Information for Your Platform. The default value is 9600 .
Is baud rate bits per second?
Summary. Baud rate is the measure of the number of changes to the signal (per second) that propagate through a transmission medium. The baud rate may be higher or lower than the bit rate, which is the number of bits per second that the user can push through the transmission system.
How accurate does the UART baud rate need to be?
Thus, our is-it-accurate-enough condition is the following: because we said that the acceptable sampling window for the last data bit is from 50% (the ideal value) to 80% (as close to the transition as we are willing to go), and 80% – 50% = 30% = 0.3.
So presuming that both UARTs are attempting to communicate at exactly the same bit rate (baud), the allowable error can be shared, in any proportion, between the two UARTs. Making use of the allowable error budget is helpful in systems where both ends of the link are being designed at the same time.
What is the error budget for UART normal link?
UART “normal link” is sampled reliably within 75% of bit time. For Figures 4 and 5, we can determine that the error budget is ±25% and ±37.5% from the optimal bit-center sampling point for the nasty and normal scenarios, respectively. This error is equivalent to ±4 or ±6 periods of the 16x UART receive clock.
How to calculate the clock mismatch for UART?
(16 internal clock cycles per bit) × (1 start bit + 8 data bits + ½ a stop bit) = (16) × (9.5) = 152 UART receive clocks after the original falling edge of the START bit. Now we can calculate our allowable error as a percentage. For the normal scenario, the clock mismatch error can be ±5/152 = ±3.3%.