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参数资料
| 型号： | ST6235BQ1/XXX |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 微控制器/微处理器 |
| 英文描述： | 8-BIT, MROM, 8 MHz, MICROCONTROLLER, PQFP52 |
| 封装： | PLASTIC, QFP-52 |
| 文件页数： | 28/82页 |
| 文件大小： | 617K |
| 代理商： | ST6235BQ1/XXX |
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ST62T35B/E35B
I/O PORTS (Cont’d)
4.1.2 Safe I/O State Switching Sequence
Switching the I/O ports from one state to another
should be done in a sequence which ensures that
no unwanted side effects can occur. The recom-
mended safe transitions are illustrated in Figure
19.. All other transitions are potentially risky and
should be avoided when changing the I/O operat-
ing mode, as it is most likely that undesirable side-
effects will be experienced, such as spurious inter-
rupt generation or two pins shorted together by the
analog multiplexer.
Single bit instructions (SET, RES, INC and DEC)
should be used with great caution on Ports Data
registers, since these instructions make an implicit
read and write back of the entire register. In port
input mode, however, the data register reads from
the input pins directly, and not from the data regis-
ter latches. Since data register information in input
mode is used to set the characteristics of the input
pin (interrupt, pull-up, analog input), these may be
unintentionally reprogrammed depending on the
state of the input pins. As a general rule, it is better
to limit the use of single bit instructions on data
registers to when the whole (8-bit) port is in output
mode. In the case of inputs or of mixed inputs and
outputs, it is advisable to keep a copy of the data
register in RAM. Single bit instructions may then
be used on the RAM copy, after which the whole
copy register can be written to the port data regis-
ter:
SET bit, datacop y
LD a, datacopy
LD DRA, a
Care must also be taken to not use INC or DEC in-
structions on a port register when the 8 bits are not
available on the devices.
The WAIT and STOP instructions allow the
ST62xx to be used in situations where low power
consumption is needed. The lowest power con-
sumption is achieved by configuring I/Os in input
mode with well-defined logic levels.
The user must take care not to switch outputs with
heavy loads during the conversion of one of the
analog inputs in order to avoid any disturbance to
the conversion.
Figure 19. Diagram showing Safe I/O State Transitions
Note *. xxx = DDR, OR, DR Bits respectively
Interrupt
pull-up
Output
Open Drain
Output
Push-pull
Input
pull-up (Reset
state)
Input
Analog
Output
Open Drain
Output
Push-pull
Input
010*
000
100
110
011
001
101
111
33
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ST6235BQ3 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:8-BIT OTP/EPROM MCUs WITH A/D CONVERTER, 16-BIT AUTO-RELOAD TIMER, EEPROM, SPI AND UART |
| ST6235BQ3/XXX | 制造商:未知厂家 制造商全称:未知厂家 功能描述:8-Bit Microcontroller |
| ST6235BQ6 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:8-BIT OTP/EPROM MCUs WITH A/D CONVERTER, 16-BIT AUTO-RELOAD TIMER, EEPROM, SPI AND UART |
| ST6235BQ6/XXX | 制造商:未知厂家 制造商全称:未知厂家 功能描述:8-Bit Microcontroller |
| ST623X | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:8/16-Bit Micros |
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