Chapter 16. UART Modules
16-19
UART Module Signal Definitions
16.4 UART Module Signal Definitions
Figure 16-21 shows both the external and internal signal groups.
Figure 16-21. UART Block Diagram Showing External and Internal Interface Signals
An internal interrupt request signal (IRQ) is provided to notify the interrupt controller of an
interrupt condition. The output is the logical NOR of unmasked UISRn bits. The interrupt
levels of the UART modules are programmed in SIM register ICR2. See Section 7.2,
“Interrupt Controller Registers.”
Table 16-15 briefly describes the UART module signals.
NOTE:
The terms ‘assertion’ and ‘negation’ are used to avoid
confusion between active-low and active-high signals.
‘Asserted’ indicates that a signal is active, independent of the
voltage level; ‘negated’ indicates that a signal is inactive.
Table 16-15. UART Module Signals
Signal
Description
Transmitter Serial
Data Output
(URT_TxD)
URT_TxD is held high (mark condition) when the transmitter is disabled, idle, or operating in the
local loop-back mode. Data is shifted out on URT_TxD on the falling edge of the clock source,
with the least significant bit (lsb) sent first.
Receiver Serial
Data Input
(URT_RxD)
Data received on URT_RxD is sampled on the rising edge of the clock source, with the lsb
received first.
Clear-to-Send
(URT_CTS)
This input can generate an interrupt on a change of state.
Internal
Receive Buffer
Transmit Buffer
Input Port
Output Port
Interface
UART Module
Address Bus
Control
Control
Logic
or
Internal Bus
Data
to CPU
IRQ
To Interrupt
Controller
(SIM)
External
Interface
Signals
CLKIN
Clock Source
Generator
URT_CTS
URT_RTS
URT_RxD
URT_TxD
External clock (URT_CLK)
24-Character
24-Character
Summary of Contents for DigitalDNA ColdFire MCF5272
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Page 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
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