78
F. Firouzi et al.
• Parity Bit – A bit that detects errors in each set of transmitted bits. In “odd parity,”
the total complete number of 1s in the transmit data when added together is equal
to an odd number. On the other hand, in “even parity,” the number of 1s in the
transfer data including the parity bit itself should be an even number.
• Bit Rate – In literature, bit rate is also referred to as total physical layer bit rate,
data signal rate, raw bit rate, or total data transfer rate. Bit rate indicates the total
number of transmitted bits per second (bps).
– Gross Bit Rate – This parameter captures both protocol overhead (e.g., start
and stop bit) and useful data.
– Net Bit Rate – Unlike the gross bit rate, this parameter indicates a digital
communication channel’s capacity and excludes overhead protocol. Net bit
rate is also known as information rate, useful bit rate, net data transfer rate,
payload rate, effective data rate, and wire speed.
• Baud Rate – This parameter also referred to as “symbol rate.” Baud rate shows
the number of symbol or signal changes occurring per second. A symbol can be
a change in phase, voltage, or frequency. Each symbol can represent one or more
bits. Based on this, the baud rate is always lower than or equal to the bit rate. The
baud rate is never higher than a bit rate. For example, if a symbol rate is 4800
baud with each symbol representing two bits, then the total bit rate is 9600 bps.
In the case of UART, each symbol represents only one bit; therefore, the baud
rate and gross bit rate are equal.
UART protocols follow the following steps to exchange data between two
devices:
1. UART module in the transmitter device receives parallel data from the data bus.
2. UART modules create the UART packet including start, parity, stop bits, as well
as the payload (actual intended message).
3. The whole data packet is sent via the bus in series to receiving UART module in
the receiver device.
4. Receiving UART module samples bus at a preset baud rate.
5. Receiving UART module removes start, parity, and stop bits and extracts the
payload.
6. Receiving UART module formats the received serial data (payload) and publishes
it to the data bus of the receiver device.
2.5.3.6 Serial Peripheral Interface (SPI)
Serial Peripheral Interface (SPI) is often used to transmit data between small
peripherals (e.g., sensors and SD cards) and their corresponding microcontrollers.
While asynchronous serial communication can also be used to address this situation, it requires complicated hardware for data transmission, and also it includes
significant overhead because of extra start and stop bits that are packaged with each
payload (actual intended message). On the other hand, SPI is a synchronous data
F. Firouzi et al.
• Parity Bit – A bit that detects errors in each set of transmitted bits. In “odd parity,”
the total complete number of 1s in the transmit data when added together is equal
to an odd number. On the other hand, in “even parity,” the number of 1s in the
transfer data including the parity bit itself should be an even number.
• Bit Rate – In literature, bit rate is also referred to as total physical layer bit rate,
data signal rate, raw bit rate, or total data transfer rate. Bit rate indicates the total
number of transmitted bits per second (bps).
– Gross Bit Rate – This parameter captures both protocol overhead (e.g., start
and stop bit) and useful data.
– Net Bit Rate – Unlike the gross bit rate, this parameter indicates a digital
communication channel’s capacity and excludes overhead protocol. Net bit
rate is also known as information rate, useful bit rate, net data transfer rate,
payload rate, effective data rate, and wire speed.
• Baud Rate – This parameter also referred to as “symbol rate.” Baud rate shows
the number of symbol or signal changes occurring per second. A symbol can be
a change in phase, voltage, or frequency. Each symbol can represent one or more
bits. Based on this, the baud rate is always lower than or equal to the bit rate. The
baud rate is never higher than a bit rate. For example, if a symbol rate is 4800
baud with each symbol representing two bits, then the total bit rate is 9600 bps.
In the case of UART, each symbol represents only one bit; therefore, the baud
rate and gross bit rate are equal.
UART protocols follow the following steps to exchange data between two
devices:
1. UART module in the transmitter device receives parallel data from the data bus.
2. UART modules create the UART packet including start, parity, stop bits, as well
as the payload (actual intended message).
3. The whole data packet is sent via the bus in series to receiving UART module in
the receiver device.
4. Receiving UART module samples bus at a preset baud rate.
5. Receiving UART module removes start, parity, and stop bits and extracts the
payload.
6. Receiving UART module formats the received serial data (payload) and publishes
it to the data bus of the receiver device.
2.5.3.6 Serial Peripheral Interface (SPI)
Serial Peripheral Interface (SPI) is often used to transmit data between small
peripherals (e.g., sensors and SD cards) and their corresponding microcontrollers.
While asynchronous serial communication can also be used to address this situation, it requires complicated hardware for data transmission, and also it includes
significant overhead because of extra start and stop bits that are packaged with each
payload (actual intended message). On the other hand, SPI is a synchronous data