psd934f2v-20mi STMicroelectronics, psd934f2v-20mi Datasheet - Page 42

• Manufacturer Part Number: psd934f2v-20mi
• Description: Flash In-system Programmable Isp Peripherals For 8-bit Mcus
• Manufacturer: STMicroelectronics

The
PSD9XX
Functional
Blocks
(cont.)
38
PSD9XX Family
9.3.3.3 80C51XA
The Philips 80C51XA microcontroller family supports an 8- or 16-bit multiplexed bus that
can have burst cycles. Address bits A[3:0] are not multiplexed, while A[19:4] are
multiplexed with data bits D[15:0] in 16-bit mode. In 8-bit mode, A[11:4] are multiplexed
with data bits D[7:0].
The 80C51XA can be configured to operate in eight-bit data mode. (shown in Figure 17).
The 80C51XA improves bus throughput and performance by executing Burst cycles for
code fetches. In Burst Mode, address A19-4 are latched internally by the PSD9XX, while
the 80C51XA changes the A3-0 lines to fetch up to 16 bytes of code. The PSD access
time is then measured from address A3-A0 valid to data in valid. The PSD bus timing
requirement in Burst Mode is identical to the normal bus cycle, except the address setup
and hold time with respect to ALE does not apply.
9.3.3.4 68HC11
Figure 18 shows an interface to a 68HC11 where the PSD9XX is configured in 8-bit
multiplexed mode with E and R/W settings. The DPLD can generate the READ and WR
signals for external devices.
Table 19. 80C251 Configurations
Configuration
1
2
3
4
Read/Write
WR
RD
PSEN
WR
PSEN only
WR
PSEN only
WR
RD
PSEN
80C251
Pins
Connecting to
PSD9XX
CNTL0
CNTL1
CNTL2
CNTL0
CNTL1
CNTL0
CNTL1
CNTL0
CNTL1
CNTL2
Pins
Non-Page Mode, 80C31 compatible
A
Non-Page Mode
A
Page Mode
A
Page Mode
A
[
[
[
[
7:0
7:0
15:8
15:8
]
]
]
]
multiplex with D
multiplex with D
multiplex with D
multiplex with D
Page Mode
Preliminary Information
[
[
7:0
7:0
[
[
7:0
7:0
}
}
}
}