zpsd211r STMicroelectronics, zpsd211r Datasheet - Page 20

• Manufacturer Part Number: zpsd211r
• Description: Low Cost Field Programmable Microcontroller Peripherals
• Manufacturer: STMicroelectronics

12.0
Control Signals
(Cont.)
12.1 ALE or AS
Connect the ALE or AS signal from your MCU to this pin where applicable, and program
the polarity using PSDsoft. The trailing edge (when the signal goes inactive) of ALE or AS
latches the address on the appropriate address pins.
12.2 WR or R/W
Your MCU should output a stand-alone write signal (WR) or a multiplexed read/write signal
(R/W). In either case, the signal should be connected to this pin.
12.3 RD/E
Your MCU should output either RD or E (clock). In either case, connect the appropriate
signal to this pin. Note: if you have an MCU that outputs DS, it will not be compatible with
the PSD211R, and you must use a PSD3XX family device.
12.4 PSEN
12.5 A19/CSI
This pin is configured using PSDsoft to be either a chip select for the entire PSD device or
an additional PAD input. If your MCU can generate a chip-select signal, and you wish to
save power, use the PSD chip select feature. Otherwise, use this pin as an address or logic
input.
Table 7A. Signal States During Power-down Mode
AD0–AD15
Port Pins PA0–PA7
Port Pins PB0–PB7
Port Pins PC0–PC2
If your MCU does not output PSEN (or some program select enable equivalent signal),
tie this pin to Vcc (through a series resistor), and skip to the next signal.
If you use an 8-bit 8031 compatible MCU that outputs a separate signal when
accessing program space, such as PSEN, connect it to this pin. You would then use
PSDsoft to configure the EPROM in the PSD211R to respond to PSEN only or PSEN
and RD. If you have an 8031 compatible MCU, refer to the “Program/Data Space and
the 8031” section for further information.
When configured as CSI (active-low PSD chip select): a low on this pin keeps the
PSD in normal operation. However, when a high is detected on the pin, the PSD
enters Power-down Mode. See Tables 7A and 7B for information on signal states
during Power-down Mode. See section 16 for details about the reduction of power
consumption.
When configured as A19, the pin can be used as an additional input to the PADs.
It can be used for address or logic. It can also be ALE/AS dependent or a transparent
input, which is determined by your PSDsoft design file. In A19 mode, the PSD is
always enabled.
Port
All
MCU I/O
Latched Address Out
MCU I/O
Chip Select Outputs, CS0–CS7, CMOS
Chip Select Outputs, CS0–CS7, Open Drain
Address or Logic Inputs, A16-A18
Chip Select Outputs, CS8–CS10, CMOS only
Configuration Mode(s)
PSD211R Family
Unchanged
Unchanged
Input (Hi-Z)
Input (Hi-Z)
Logic 1
Logic 1
Logic 1
State
Hi-Z
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