參數(shù)資料
型號: uPSD3234AV-40U6T
廠商: 意法半導(dǎo)體
英文描述: Flash Programmable System Devices with 8032 Microcontroller Core
中文描述: 閃存可編程系統(tǒng)設(shè)備與8032微控制器內(nèi)核
文件頁數(shù): 104/170頁
文件大?。?/td> 2717K
代理商: UPSD3234AV-40U6T
uPSD3234A, uPSD3234BV, uPSD3233B, uPSD3233BV
104/170
Programming Flash Memory
Flash memory must be erased prior to being pro-
grammed. A byte of Flash memory is erased to all
'1s' (FFh), and is programmed by setting selected
bits to '0.' The MCU may erase Flash memory all
at once or by-sector, but not byte-by-byte. Howev-
er, the MCU may program Flash memory byte-by-
byte.
The primary and secondary Flash memories re-
quire the MCU to send an instruction to program a
byte or to erase sectors (see
Table 85., page 101
).
Once the MCU issues a Flash memory Program or
Erase instruction, it must check for the status bits
for completion. The embedded algorithms that are
invoked support several means to provide status
to the MCU. Status may be checked using any of
three methods: Data Polling, Data Toggle, or
Ready/Busy (PC3).
Data Polling.
Polling on the Data Polling Flag Bit
(DQ7) is a method of checking whether a Program
or Erase cycle is in progress or has completed.
Figure
52
shows the Data Polling algorithm.
When the MCU issues a Program instruction, the
embedded algorithm begins. The MCU then reads
the location of the byte to be programmed in Flash
memory to check status. The Data Polling Flag Bit
(DQ7) of this location becomes the complement of
b7 of the original data byte to be programmed. The
MCU continues to poll this location, comparing the
Data Polling Flag Bit (DQ7) and monitoring the Er-
ror Flag Bit (DQ5). When the Data Polling Flag Bit
(DQ7) matches b7 of the original data, and the Er-
ror Flag Bit (DQ5) remains '0,' the embedded algo-
rithm is complete. If the Error Flag Bit (DQ5) is '1,'
the MCU should test the Data Polling Flag Bit
(DQ7) again since the Data Polling Flag Bit (DQ7)
may have changed simultaneously with the Error
Flag Bit (DQ5) (see Figure
52
).
The Error Flag Bit (DQ5) is set if either an internal
time-out occurred while the embedded algorithm
attempted to program the byte or if the MCU at-
tempted to program a '1' to a bit that was not
erased (not erased is logic '0').
It is suggested (as with all Flash memories) to read
the location again after the embedded program-
ming algorithm has completed, to compare the
byte that was written to the Flash memory with the
byte that was intended to be written.
When using the Data Polling method during an
Erase cycle, Figure
52
still applies. However, the
Data Polling Flag Bit (DQ7) is '0' until the Erase cy-
cle is complete. A '1' on the Error Flag Bit (DQ5) in-
dicates a time-out condition on the Erase cycle; a
'0' indicates no error. The MCU can read any loca-
tion within the sector being erased to get the Data
Polling Flag Bit (DQ7) and the Error Flag Bit
(DQ5).
PSDsoft Express generates ANSI C code func-
tions which implement these Data Polling algo-
rithms.
Figure 52. Data Polling Flowchart
READ DQ5 & DQ7
at VALID ADDRESS
START
READ DQ7
FAIL
PASS
AI01369B
D=
DATA
YES
NO
YES
NO
DQ5
= 1
D=
DATA
YES
NO
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