System Overview
3-15
X1
Crystal Input (input)
This pin and the X2 pin provide connections for a fundamental mode
or third-overtone parallel-resonant crystal used by the internal oscillator
circuit. To provide the microcontroller with an external clock source,
connect the source to the X1 pin and leave the X2 pin unconnected.
X2
Crystal Output (output)
This pin and the X1 pin provide connections for a fundamental mode
or third-overtone parallel-resonant crystal used by the internal oscillator
circuit. To provide the microcontroller with an external clock source,
leave the X2 pin unconnected and connect the source to the X1 pin.
3.1.1
Pins That Are Used by Emulators
The following pins are used by emulators: A19–A0, AO15–AO8, AD7–AD0, ALE, BHE/
ADEN (on the Am186EM), CLKOUTA, RFSH2/ADEN (on the Am188EM), RD, S2–S0, S6/
CLKDIV2, and UZI.
Emulators require that S6/CLKDIV2 and UZI be configured in their normal functionality,
that is, as S6 and UZI.
If BHE/ADEN (on the Am186EM) or RFSH2/ADEN (on the Am188EM) is held Low during
the rising edge of RES, S6 and UZI are configured in their normal functionality, instead of
as PIOs, at reset.
Summary of Contents for AM186EM
Page 1: ...Am186 EM and Am188 EM Microcontrollers User s Manual...
Page 4: ...iv...
Page 12: ...Table of Contents xii...
Page 62: ...Peripheral Control Block 4 10...
Page 76: ...Chip Select Unit 5 14...
Page 122: ...Timer Control Unit 8 8...
Page 136: ...DMA Controller 9 14...
Page 144: ...Asynchronous Serial Port 10 8...
Page 158: ...Programmable I O Pins 12 6...
Page 186: ...Index I 12...