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| 型号： | PSD301-20JI |
| 厂商： | 意法半导体 |
| 英文描述： | Low Cost Field Programmable Microcontroller Peripherals |
| 中文描述： | 低成本现场可编程微控制器外围设备 |
| 文件页数： | 19/85页 |
| 文件大小： | 691K |
| 代理商： | PSD301-20JI |
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PSD3XX Famly
16
10.0
I/OPort
Functions
(
cont.)
10.2 Port A (PA0-PA7)
The control registers of Port A are located in CSIOPORT space; see Table 5.
10.2.1 Port A (PA0-PA7) in Multiplexed Address/Data Mode
Each pin of Port A can be individually configured. The following table summarizes what the
control registers (in CSIOPORT space) for Port A do:
NOTE:
1. Default value is the value after reset.
Default
Value
(Note 1)
Register Name
0 Value
1 Value
Port A Pin Register
Sampled logic level
at pin = ‘0’
Pin is configured
as input
Data in DFF = ‘0’
Sampled logic level
at pin = ‘1’
Pin is configured
as output
Data in DFF = ‘1’
X
Port A Direction Register
0
Port A Data Register
0
MCUI/OMode
The default configuration of Port A is MCU I/O. In this mode, every pin can be set (at run-
time) as an input or output by writing to the respective pin’s direction flip-flop (DIR FF,
Figure 5A). As an output, the pin level can be controlled by writing to the respective pin’s
data flip-flop (DFF, Figure 5A). The Pin Register can be read to determine logic level of the
pin. The contents of the Pin Register indicate the true state of the PSD driving the pin
through the DFF or an external source driving the pin. Pins can be configured as CMOS
or open-drain using
ST
’s PSDsoft software. Open-drain pins require external pull-up
resistors.
Latched Address Output Mode
Alternatively, any bit(s) of Port A can be configured to output low-order demultiplexed
address bus bit. The address is provided by the internal PSD address latch, which latches
the address on the trailing edge of ALE/AS. Port A then outputs the desired demultiplexed
address bits. This feature can eliminate the need for an external latch (for example:
74LS373) if you have devices that require low-order latched address bits. Although any pin
of Port A may output an address signal, the pin is position-dependent. In other words, pin
PA0 of Port A may only pass A0, PA1 only A1, and so on.
Track Mode
Track Mode sets the entire port to track the signals on AD0/A0-AD7/A7, depending on
specific address ranges defined by the PAD’s CSADIN, CSADOUT1, and CSADOUT2
signals. This feature lets the user interface the microcontroller to shared external resources
without requiring external buffers and decoders. In Track Mode, Port A effectively operates
as a bi-directional buffer, allowing external MCUs or host processors to access the local
data bus. Keep the following information in mind when setting up Track Mode:
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The direction is controlled by:
ALE/AS
RD/E or RD/E/DS (DS on non-3X1 devices only)
WR or R/W
PAD outputs CSADOUT1, CSADOUT2, and CSADIN defined in PSDsoft design.
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When CSADOUT1 and ALE/AS are true, the address on AD0/A0-AD7/A7 is output on
Port A. Note: carefully check the generation of CSADOUT1 to ensure that it is stable
during the ALE/AS pulse.
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When CSADOUT2 is active and a write operation is performed, the data on the
AD0/A0-AD7/A7 input pins flows out through Port A.
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When CSADIN is active and a read operation is performed, the data on Port A flows
out through the AD0/A0-AD7/A7 pins.
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Port A is tri-stated when none of the above conditions exist.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| PSD301-20JM | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:Low Cost Field Programmable Microcontroller Peripherals |
| PSD301-20LI | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Field-Programmable Peripheral |
| PSD301-20LM | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Field-Programmable Peripheral |
| PSD301-20Q | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Field-Programmable Peripheral |
| PSD301-20QI | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Field-Programmable Peripheral |
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