System Overview
Am186™CC/CH/CU Microcontrollers User’s Manual
3-15
RES
—
STI
Reset requires the microcontroller to perform a reset. When RES
is asserted, the microcontroller immediately terminates its
present activity, clears its internal logic, and on the deassertion
of RES, transfers CPU control to the reset address FFFF0h.
RES must be asserted for at least 1 ms to allow the internal
circuits to stabilize.
RES can be asserted asynchronously to CLKOUT because RES
is synchronized internally. For proper initialization, V
CC
must be
within specifications, and CLKOUT must be stable for more than
four CLKOUT periods during which RES is asserted.
If RES is asserted while the watchdog timer is performing a
watchdog-timer reset, the external reset takes precedence over
the watchdog-timer reset. This means that the RESOUT signal
asserts as with any external reset and the WDTCON register
will not have the RSTFLAG bit set. In addition, the microcontroller
will exit reset based on the external reset timing, i.e., 4.5 clocks
after the deassertion of RES rather than 2
16
clocks after the
watchdog timer timeout occurred.
The microcontroller begins fetching instructions approximately
6.5 CLKOUT periods after RES is deasserted. This input is
provided with a Schmitt trigger to facilitate power-on RES
generation via a resistor-capacitor (RC) network.
RESOUT
—
O
Reset Out indicates that the microcontroller is being reset (either
externally or internally), and the signal can be used as a system
reset to reset any external peripherals connected to RESOUT.
During an external reset, RESOUT remains active (High) for two
clocks after RES is deasserted. The microcontroller exits reset
and begins the first valid bus cycle approximately 4.5 clocks after
RES is deasserted.
[UCLK]
[USBSOF]
[USBSCI]
PIO21
STI
UART Clock can be used instead of the processor clock as the
source clock for either the UART or the High-Speed UART. The
source clock for the UART and the High-Speed UART are
selected independently and both can use the same source.
USBX1
USBX2
—
—
STI
O
USB Controller Crystal Input (USBX1) and USB Controller
Crystal Output (USBX2) provide connections for a fundamental
mode, parallel-resonant crystal used by the internal USB
oscillator circuit.
If the CPU crystal is used to generate the USB clock, USBX1
must be pulled down.
X1
X2
—
—
O
STI
CPU Crystal Input (X1) and CPU Crystal Output (X2) provide
connections for a fundamental mode, parallel-resonant crystal
used by the internal oscillator circuit. If an external oscillator is
used, inject the signal directly into X1 and leave X2 floating.
Table 3-7
Signal Descriptions (Continued)
Signal Name
1
Multiplexed
Signal(s)
Type Description
CC
CU
CC
CU
Summary of Contents for Am186 CC
Page 1: ...Am186 CC CH CU Microcontrollers User s Manual Order 21914B...
Page 4: ...iv Am186 CC CH CU Microcontrollers User s Manual...
Page 18: ...Table of Contents xviii Am186 CC CH CU Microcontrollers User s Manual...
Page 24: ...Introduction xxiv Am186 CC CH CU Microcontrollers User s Manual...
Page 40: ...Architectural Overview 1 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 86: ...System Overview 3 36 Am186 CC CH CU Microcontrollers User s Manual...
Page 92: ...Emulator Support 4 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 112: ...DRAM Controller 6 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 134: ...Interrupts 7 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 186: ...Programmable I O Signals 9 8 Am186 CC CH CU Microcontrollers User s Manual...
Page 200: ...Watchdog Timer 11 6 Am186 CC CH CU Microcontrollers User s Manual...
Page 232: ...Asynchronous Serial Ports UARTs 13 24 Am186 CC CH CU Microcontrollers User s Manual...
Page 242: ...Synchronous Serial Port SSI 14 10 Am186 CC CH CU Microcontrollers User s Manual...
Page 264: ...High Level Data Link Control HDLC 15 22 Am186 CC CH CU Microcontrollers User s Manual...
Page 332: ...Universal Serial Bus USB 18 34 Am186 CC CH CU Microcontrollers User s Manual...
Page 348: ...Register Summary A 16 Am186 CC CH CU Microcontrollers User s Manual...
Page 376: ...Index Index 18 Am186 CC CH CU Microcontrollers User s Manual...