
UM10413
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© NXP B.V. 2011. All rights reserved.
User manual
Rev. 1 — 16 December 2011
91 of 268
NXP Semiconductors
UM10413
MPT612 User manual
14.4 Architecture
The architecture of UART0 is shown in block diagram
.
The APB 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.
The UART0 transmitter block, U0TX, accepts data written by the CPU or host and buffers
the data in the UART0 TX Holding register FIFO (U0THR). The UART0 TX Shift register
(U0TSR) reads the data stored in the U0THR and assembles the data to transmit via the
serial output pin TXD0.
a. Mode 0 (start bit and LSB are used for auto-baud)
b. Mode 1 (only start bit is used for auto-baud)
Fig 19. Autobaud mode 0 and mode 1 waveforms
aaa-000636
UART0 RX
U0ACR start
rate counter
'A' (0x41) or 'a' (0x61)
16 cycles
16 cycles
16xbaud_rate
LSB of 'A' or 'a'
start bit
start
bit0
bit1
bit2
bit3
bit4
bit5
bit6
bit7
parity
stop
aaa-000582
UART0 RX
LSB of 'A' or 'a'
start bit
rate counter
'A' (0x41) or 'a' (0x61)
start
bit0
bit1
bit2
bit3
bit4
bit5
bit6
bit7
parity
stop
U0ACR start
16 cycles
16xbaud_rate