7.4. Data Transmission and Reception in AHB UART

● Transmission: ○ The CPU writes data to the Data Register. This data is then transferred to the Transmit FIFO buffer. ○ The UART peripheral converts the data into a serial bitstream, which is transmitted over the TX pin to the external device. ○ Baud Rate Control: The timing of each bit sent is controlled by the configured baud rate.

In the data transmission process, the CPU sends data to the AHB UART peripheral by writing it to the Data Register. This data is first stored in a temporary area called the Transmit FIFO buffer. The UART then takes this data, converts it from its parallel form into a serial bitstream (which is a sequence of bits sent one after the other), and sends it out through the TX pin to an external device. The speed at which these bits are sent is controlled by something called the baud rate, which is set in advance to ensure that both the sender and receiver are synchronized in terms of timing.

Think of this process like a conveyor belt in a factory. The CPU is like a worker putting items (data) on the belt (Data Register), the FIFO buffer is the temporary holding area where items wait until they are ready to be sent (Transmit FIFO buffer), and the UART is the machine that takes these items one by one, converts them into a format suitable for delivery (serial bitstream), and then sends them to another location (external device) based on the speed defined (baud rate).

● Reception: ○ Data received over the RX pin is stored in the Receive FIFO buffer. ○ The CPU can read data from the Data Register when it is ready, processing incoming serial data. ○ Interrupts: The UART peripheral can generate interrupts to notify the CPU when data is ready to be read or when an error occurs (e.g., buffer overrun).

In the data reception process, the UART peripheral listens for incoming data on the RX pin. As this data arrives, it is temporarily stored in the Receive FIFO buffer. The CPU can then access this data by reading from the Data Register when it's ready to process the incoming information. Additionally, the UART is capable of generating interrupts, which are signals that alert the CPU that certain events have occurred, such as receiving new data or encountering an error (like having too much data that can't all fit in the buffer).

This is similar to a mailbox system. The RX pin acts like a mailbox that receives letters (data). The mailbox holds these letters in a waiting area (Receive FIFO buffer) until the postal worker (the CPU) is ready to collect and read them (by reading from the Data Register). When a letter arrives, a bell can ring (interrupt) to notify the worker that there’s something to pick up. If too many letters arrive at once and the mailbox gets full, an alert is triggered to indicate the mailbox is overflowing (buffer overrun).

--