EZ80190AZ050SC00TR Zilog, EZ80190AZ050SC00TR Datasheet - Page 79

• Manufacturer Part Number: EZ80190AZ050SC00TR
• Description: IC EZ80 ACCLAIM 50MHZ 100LQFP
• Manufacturer: Zilog

Specifications of EZ80190AZ050SC00TR

• Processor Type: eZ80
• Features: High Speed, Single-Cycle Instruction-Fetch
• Speed: 50MHz
• Voltage: 3.3V
• Mounting Type: Surface Mount
• Package / Case: 100-LQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

PS006614-1208
UART Receiver
UART Modem Control
ister) is set to 1 and an interrupt is sent to the processor (if interrupts are enabled). The pro-
cessor can reset this interrupt by loading data into the UARTx_THR register, which clears
the transmitter interrupt.
The transmit shift register places the byte to be transmitted on the TXD signal serially. The
lsb of the byte to be transmitted is shifted out first and the msb is shifted out last. The con-
trol logic within the block adds the asynchronous communications protocol bits to the data
byte being transmitted. The transmitter block obtains the parameters for the protocol from
the bits programmed through the UARTx_LCTL register. The TXD output is set to 1 if the
transmitter is idle (it does not contain any data to be transmitted).
The transmitter operates with the Baud Rate Generator (BRG) clock. The data bits are
placed on the TXD output one time every 16 BRG clock cycles. The transmitter block also
implements a parity generator and attaches the parity bit with the byte if programmed to
do so.
The receiver block controls data reception from the RXD signal. The receiver block
implements a receiver shift register, receiver line error condition monitoring logic and
receiver data ready logic. It also implements a parity checker.
The processor reads received data from UARTx_RBR, which is a Read Only register. The
condition of the UARTx_RBR register is monitored by the DR bit (bit 0 of the
UARTx_LSR register). The DR bit is set to 1 when a data byte is received and transferred
to the UARTx_RBR register from the receiver shift register. The DR bit is reset only when
the processor reads all received data bytes. If the number of bits received is less than eight,
the unused msbs of the data byte read are reset to 0.
The receiver uses the clock from the BRG input of the UZI for receiving data. This clock
must be 16 times the required baud rate. The receiver synchronizes the shift clock on the
falling edge of the RXD input start bit. It then receives a complete byte according to the
set parameters. The receiver also implements logic to detect framing errors, parity errors,
overrun errors, and break signals.
The modem control logic provides two outputs and four inputs for handshaking with the
modem. Any change in the modem status inputs, except RI, is detected. An interrupt can
then be generated. For RI, an interrupt is generated only when the trailing edge of the RI is
detected. The module also provides a loop mode for self-diagnostic purposes.
Universal Asynchronous Receiver/Transmitter
Product Specification
eZ80190
69