|
MCF5307AI90B Datasheet, PDF (372/484 Pages) Freescale Semiconductor, Inc – Integrated Microprocessor | |||
|
◁ |
Freescale Semiconductor, Inc.
MCF5307 Bus Signals
⢠A[31:24]âPins are conï¬gured as address bits by setting corresponding PAR bits;
they represent the most-signiï¬cant address bus bits. As much as 4 Gbytes of
memory are available when all of these pins are programmed as address signals.
⢠PP[15:8]âPins are conï¬gured as parallel port signals by clearing corresponding
PAR bits; these represent the most-signiï¬cant parallel port bits.
17.2.2 Data Bus (D[31:0])
The data bus is bidirectional and non-multiplexed. Data is sampled by the MCF5307 on the
rising BCLKO edge. The data bus port width, wait states, and internal termination are
initially deï¬ned for the boot chip select by D[7:0] during reset. The port width for each chip
select and DRAM bank are programmable. The data bus uses a default conï¬guration if none
of the chip selects or DRAM bank match the address decode. The default conï¬guration is
a 32-bit port with external termination and burst-inhibited transfers. The data bus can
transfer byte, word, or longword data widths. All 32 data bus signals are driven during
writes, regardless of port width and operand size.
D[7:0] are used during reset initialization as inputs to conï¬gure the functions as described
in Table 17-3. They are deï¬ned in Section 17.5.5, âData/Conï¬guration Pins (D[7:0]).â
Table 17-3. Data Pin Configuration
Pin
Function
Section
D7 Auto-acknowledge conï¬guration
(AA_CONFIG)
Section 17.5.5.2, âD7âAuto Acknowledge Conï¬guration
(AA_CONFIG)â
D[6:5] Port size conï¬guration (PS_CONFIG[1:0]) Section 17.5.5.3, âD[6:5]âPort Size Conï¬guration
(PS_CONFIG[1:0])â
D4 Address conï¬guration (ADDR_CONFIG/D4) Section 17.5.6, âD4âAddress Conï¬guration
(ADDR_CONFIG)â
D[3:2] Frequency Control PLL (FREQ[1:0])
Section 17.5.7, âD[3:2]âFrequency Control PLL (FREQ[1:0] )
D[1:0] Divide Control (DIVIDE[1:0])
Section 17.5.8, âD[1:0]âDivide Control PCLK to BCLKO
(DIVIDE[1:0])
17.2.3 Read/Write (R/W)
When the MCF5307 is the bus master, it drives the R/W signal to indicate the direction of
subsequent data transfers. It is driven high during read bus cycles and driven low during
write bus cycles. This signal is an input during an external master access.
17.2.4 Size (SIZ[1:0])
When it is the bus master, the MCF5307 outputs these signals to indicate the requested data
transfer size. Table 17-4 shows the deï¬nition of the bus request size encodings. When the
MCF5307 device is not the bus master, these signals function as inputs.
Note that for misaligned transfers, SIZ[1:0] indicate the size of each transfer. For example,
if a longword access occurs at a misaligned offset of 0x1, a byte is transferred ï¬rst (SIZ[1:0]
17-8
MCF5307 Userâs Manual
For More Information On This Product,
Go to: www.freescale.com
|
▷ |