AM186ES Advanced Micro Devices, AM186ES Datasheet - Page 158

• Manufacturer Part Number: AM186ES
• Description: microcontrollers provide a low-cost/ high-performance solution for embedded system designers who wish to use the x86 architecture.
• Manufacturer: Advanced Micro Devices

10.2.4
Figure 10-6
10-12
Serial Port 0/1 Receive Registers
(SP0RD/SP1RD, Offset 86h/16h)
These registers (Figure 10-6) contain data received over the serial port. The receiver is
double-buffered; the receive section can be receiving a subsequent frame of data in the
receive shift register (which is not accessible to software) while the receive data register is
being read.
The Receive-Data-Ready (RDR) bit in the serial port status register reports the current
state of this register. When the RDR bit is set, the receive register contains valid unread
data. The RDR bit is automatically cleared when the receive register is read.
When hardware handshaking is enabled, the CTS/ENRX signals are deasserted while the
receive register contains valid unread data. Reading the receive register causes the CTS/
ENRX signals to be asserted. This behavior prevents overrun errors, but may result in
delays between character transmissions.
Serial Port Receive 0/1 Registers
The value of SPRD at reset is undefined.
Bits 15–8: Reserved
Bits 7–0: Receive Data (RDATA)—This field holds valid data received over the serial line
only when the RDR bit in the associated serial port control register is set.
15
Reserved
Asynchronous Serial Port
7
RDATA
0