PSD813F2A-90JI Datasheet, PDF (65/128 Pages) STMicroelectronics – Flash in-system programmable (ISP) peripherals

PSD8XXFX
MCU bus interface
15.7 80C51XA
The Philips 80C51XA MCU family supports an 8- or 16-bit multiplexed bus that can have
burst cycles. Address bits (A3-A0) are not multiplexed, while (A19-A4) are multiplexed with
data bits (D15-D0) in 16-bit mode. In 8-bit mode, (A11-A4) are multiplexed with data bits
(D7-D0).
The 80C51XA can be configured to operate in eight-bit data mode (as shown in Figure 23).
The 80C51XA improves bus throughput and performance by executing burst cycles for code
fetches. In Burst mode, address A19-A4 are latched internally by the PSD, while the
80C51XA changes the A3-A0 signals 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 Address Strobe (ALE/AS, PD0) does not apply.
t(s) ^{Figure 23. Interfacing the PSD with the 80C51X, 8-bit data bus}
Obsolete ^{Product(s) - Obsolete Produc RESET}
80C51XA
21
20
XTAL1
XTAL2
11 _RXD0
13
6
TXD0
RXD1
7 _TXD1
9
8
T2EX
T2
16 _T0
10 _RST
14 _INT0
15
INT1
A0/WRH
A1
2
3
A2 ⁴
A3 ⁵
A4D0
A5D1
A6D2
A7D3
43
42
41
40
39
A8D4
A9D5
A10D6
A11D7
A12D8
A13D9
A14D10
A15D11
A16D12
A17D13
A18D14
38
37
36
24
25
26
27
28
29
30
31
A19D15
A0
A1
A2
A3
A4D0
A5D1
A6D2
A7D3
A8D4
A9D5
A10D6
A11D7
A12
A13
A14
A15
A16
A17
A18
A19
35 _EA/WAIT
17 _BUSW
32
PSEN
RD ¹⁹
WRL ¹⁸
33
ALE
PSEN
RD
WR
ALE
RESET
A4D0
A5D1
A6D2
A7D3
A8D4
A9D5
A10D6
A11D7
PSD
30
31
ADIO0
32
33
ADIO1
ADIO2
ADIO3
34 _AD104
35 _AD105
36
37
ADIO6
ADIO7
A12
A13
A14
A15
A16
A17
A18
A19
39
40
ADIO8
41
42
43
44
45
ADIO9
ADIO10
ADIO11
AD1012
AD1013
ADIO14
46 _ADIO15
47 _{CNTL0 (WR)}
50 _CNTL1(RD)
49
CNTL 2 (PSEN)
10
8 ^PD0-ALE
9
PD1
PD2
48
RESET
29 A0
PA0
PA1
28
A1
PA2 ^{27 A2}
PA3
PA4
PA5
25
24
23
A3
PA6 ²²
PA7 ²¹
7
PB0
PB1
PB2
PB3
PB4
6
5
4
3
2
PB5
PB6
PB7
52
51
20
PC0 ₁₉
PC1
PC2
PC3
PC4
18
17
14
PC5
PC6
13
12
PC7 ¹¹
AI02883C
Doc ID 7833 Rev 7
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