11-2
MC9328MX1 Reference Manual
MOTOROLA
External Interface Module (EIM)
11.2.3 Read/Write
The R/W output signal indicates if the current bus access is in a read or write cycle. A high (logic one)
level indicates a read cycle, and a low (logic zero) level indicates a write cycle.
11.2.4 Control Signals
The OE and EB [3:0] signals are used to control external device’s interface to the external data bus.
11.2.4.1 OE—Output Enable
This active-low output signal indicates the bus access is a read, and enable slave devices to drive the data
bus with read data.
11.2.4.2 EB [3:0]—Enable Bytes
These active-low output pins indicate active data bytes for the current access. They may be configured to
assert for read and write cycles or for write cycles only as programmed in the CS configuration registers.
EB [0] corresponds to D [31:24], EB [1] corresponds to D [23:16], EB [2] corresponds to D [15:8], and EB
[3] corresponds to D [7:0].
11.2.4.3 DTACK—Data Transfer Acknowledge
The DTACK signal is the external input data acknowledge signal that only supported by CS[5]. When the
external DTACK signal is used as a data acknowledge signal, the bus time-out monitor generates a bus
error when a bus cycle is not terminated by the external DTACK signal after 1022 clocks counts have
elapsed.
The maximum wait state supported by the DTACK signal at 96 MHz is 10.645us. This can be calculated
by dividing the number of maximum wait state cycles (in this case 1022) by the system clock frequency
(HCLK). For designs requiring a longer wait state time greater than 10.645us, it is necessary to reduce the
system clock frequency HCLK to an appropriate value that is less than 96 MHz. The system clock HCLK
can be divided by setting the BLCK_DIV bits in the Clock Source Control Register to the desired value.
For more detailed information about setting the BCLK_DIV bits, see Chapter 12, “Phase-Locked Loop
and Clock Controller.”
11.2.5 Chip Select Outputs
11.2.5.1 Chip Select 0 (CS0)
The CS0 output signal is active-low and is asserted based on a decode of internal address bus bits A[31:24]
of the accessed address, and at reset is based on the value of the BOOTMOD [3:0] inputs. The port size is
determined by the state of the BOOTMOD[3:0] inputs. See Section 8.2, “System Boot Mode Selection,”
on page 8-7 for more information.
11.2.5.2 Chip Select 1–Chip Select 5 (CS1–CS5)
The CS1 through CS5 output signals are active-low and are asserted based on a decode of the internal
address bus bits A [31:24] of the accessed address. When disabled, these pins can be used as
programmable general-purpose outputs. Table 11-1 specifies the address range for each Chip Select
output.
Summary of Contents for DragonBall MC9328MX1
Page 68: ...1 12 MC9328MX1 Reference Manual MOTOROLA Introduction ...
Page 86: ...2 18 MC9328MX1 Reference Manual MOTOROLA Signal Descriptions and Pin Assignments ...
Page 116: ...3 30 MC9328MX1 Reference Manual MOTOROLA Memory Map ...
Page 126: ...4 10 MC9328MX1 Reference Manual MOTOROLA ARM920T Processor ...
Page 160: ...8 8 MC9328MX1 Reference Manual MOTOROLA System Control ...
Page 272: ...13 32 MC9328MX1 Reference Manual MOTOROLA DMA Controller ...
Page 281: ...Programming Model MOTOROLA Watchdog Timer Module 14 9 ...
Page 282: ...14 10 MC9328MX1 Reference Manual MOTOROLA Watchdog Timer Module ...
Page 300: ...15 18 MC9328MX1 Reference Manual MOTOROLA Analog Signal Processor ASP ...
Page 438: ...18 16 MC9328MX1 Reference Manual MOTOROLA Serial Peripheral Interface Modules SPI 1 and SPI 2 ...
Page 478: ...19 40 MC9328MX1 Reference Manual MOTOROLA LCD Controller ...
Page 574: ...21 32 MC9328MX1 Reference Manual MOTOROLA Memory Stick Host Controller MSHC Module ...
Page 598: ...23 16 MC9328MX1 Reference Manual MOTOROLA Real Time Clock RTC ...
Page 670: ...24 72 MC9328MX1 Reference Manual MOTOROLA SDRAM Memory Controller ...
Page 726: ...25 56 MC9328MX1 Reference Manual MOTOROLA SmartCard Interface Module SIM ...
Page 736: ...26 10 MC9328MX1 Reference Manual MOTOROLA General Purpose Timers ...
Page 854: ...29 18 MC9328MX1 Reference Manual MOTOROLA I2C Module ...
Page 900: ...30 46 MC9328MX1 Reference Manual MOTOROLA Synchronous Serial Interface SSI ...
Page 942: ...32 26 MC9328MX1 Reference Manual MOTOROLA GPIO Module and I O Multiplexer IOMUX ...