Chip Selects
Am186™CC/CH/CU Microcontrollers User’s Manual
5-7
Figure 5-3
Chip Selectable I/O Space
5.5.3
Selecting DRAM Using the Chip Selects
UCS and LCS can be configured for DRAM support with the UDEN bit in the UMCS register
and the LDEN bit in the LMCS register, respectively. PSRAM is not supported. If both UCS
and LCS are configured for DRAM, up to two banks of 256 Kbit x 16 DRAM can be accessed.
Neither, either, or both DRAM banks can be activated.
Table 5-3 shows how the signals are configured when either UCS or LCS is configured for
DRAM.
Table 5-3
Signal Function When UCS or LCS is Configured for DRAM
Signal
Function
UCS configured for DRAM
MCS1
1
Notes:
1. Even if MCS3–MCS1 can no longer be used as chip selects, the MCS0 signal can select the en-
tire middle chip select range when MCS Only mode is enabled. Also, the MCS3–MCS1 pins are
multiplexed with programmable I/O pins. To enable their DRAM functionality, the PIO Mode and Di-
rection registers must be cleared. For more information, see Chapter 9, “Programmable I/O Sig-
nals.”
Acts as upper Column Address Strobe signal (CAS1)
MCS2
Acts as lower Column Address Strobe signal (CAS0)
MCS3
Acts as upper Row Address Strobe signal (RAS1)
UCS
UCS is held High. This means any memory device that uses UCS is disabled.
This permits the user to disable a nonvolatile memory device providing boot-
up code and replace it with DRAM memory.
LCS configured for DRAM
LCS
Acts as lower Row Address Strobe signal (RAS0)
MCS1
Acts as upper Column Address Strobe signal (CAS1)
MCS2
Acts as lower Column Address Strobe signal (CAS0)
PCS7–PCS0
Selectable
Base
Base + 2047 bytes
FFFFh
0000h
64-Kbyte
I/O Space
8 Contiguous
256-Byte
Address
Regions
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...