MC94MX21DVKN3 Freescale, MC94MX21DVKN3 Datasheet - Page 25

• Manufacturer Part Number: MC94MX21DVKN3
• Manufacturer: Freescale

Specifications of MC94MX21DVKN3

• Operating Temperature (max): 70C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

Note: All the timings are assumed that the hclk is running at 133 MHz.
3.8.3
In this mode the BMI_WRITE, BMI_READ and BMI_CLK/CS are output signals driving by the BMI
module. The output signal BMI_READ_REQ is still driving active-in on a write cycle, but it can be
ignored in this case. Instead, it is used to trigger internal logic to generate the read or write signals. Data
write cycles are continuously generated when TxFIFO is not emptied.
To issue a read cycle, the user can write a value of 1 to the READ bit of control register. This bit is cleared
automatically when the read operation is completed. A read cycle reads COUNT+1 data from the external
bus slave. The user can write a 1 to the READ bit while there is still data in the TxFIFO, but the read cycle
will not start until all data in the TxFIFO is emptied. If the read cycle begins, the write operation also
cannot begin until this read cycle complete.
In this master mode operation, Int_Clk is derived from HCLK through an integer divider DIV of BMI
control register and it is used to control the read/write cycle timing by generate WRITE and CLK/CS
signals.
Freescale Semiconductor
BMI_READ_REQ
Write setup time
Write hold time
Receive data hold time
Transfer data setup time
Transfer data hold time
Read_req hold time
Figure 10. Memory Interface Slave Mode, External Bus Master Read/Write to BMI Timing
BMI_CLK/CS
BMI_D[15:0]
BMI_WRITE
Connecting BMI to External Bus Slave Devices
Item
Table 17. External Bus Master Read/Write to BMI Timing Table
(MMD_MODE_SEL=0, MASTER_MODE_SEL=0)
Ts
MC94MX21 Technical Data, Rev. 1.5
Symbol
Ttds
TxD
Read
BMI
Ttdh
Trdh
Ttds
Trh
Th
Ts
Ttdh
Ts
Minimum
Write
BMI
RxD
11
0
3
6
6
6
Trdh
Th
Typical
–
–
–
–
–
–
Maximum
14
14
24
Last TxD
–
–
–
Trh
Read
BMI
Unit
ns
ns
ns
ns
ns
ns
Specifications
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