© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
109
Philips Semiconductors
UM10139
Volume 1
Chapter 9: UART0
9.4 Architecture
The architecture of the UART0 is shown below in the block diagram.
The VPB interface provides a communications link between the CPU or host and the
UART0.
The UART0 receiver block, U0RX, monitors the serial input line, RXD0, for valid input. The
UART0 RX Shift Register (U0RSR) accepts valid characters via RXD0. After a valid
character is assembled in the U0RSR, it is passed to the UART0 RX Buffer Register FIFO
to await access by the CPU or host via the generic host interface.
Fig 18. Autobaud Mode 0 and Mode 1 waveform
a) Mode 0 (Start bit and LSB are used for auto-baud)
b) Mode 1 (only Start bit is used for auto-baud)
UART1 Rx
Start bit
LSB of 'A' or 'a'
U1ACR Start
rate counter
UART1 Rx
Start bit
LSB of 'A' or 'a'
rate counter
start
bit0
bit1
bit2
bit3
bit4
bit5
bit6
bit7
parity stop
'A' (0x41) or 'a' (0x61)
'A' (0x41) or 'a' (0x61)
start
bit0
bit1
bit2
bit3
bit4
bit5
bit6
bit7
parity stop
U1ACR Start
16 cycles
16xbaud_rate
16 cycles
16 cycles
16xbaud_rate