|Description||Configurable Memory System on a Chip for 8-Bit Microcontrollers|
|PSD804F2V-A-20B81 Datasheet PDF : 110 Pages |
22.214.171.124 Power-Up Condition
The PSD835G2 internal logic is reset upon power-up to the read array mode. The FSi and
CSBOOTi select signals, along with the write strobe signal, must be in the false state
during power-up for maximum security of the data contents and to remove the possibility of
data being written on the first edge of a write strobe signal. Any write cycle initiation is
locked when VCC is below VLKO.
Under typical conditions, the microcontroller may read the Flash, or secondary Flash
memories using read operations just as it would a ROM or RAM device. Alternately, the
microcontoller may use read operations to obtain status information about a program or
erase operation in progress. Lastly, the microcontroller may use instructions to read
special data from these memories. The following sections describe these read functions.
126.96.36.199.1 Read the Contents of Memory
Main Flash and secodary Flash memories are placed in the read array mode after
power-up, chip reset, or a Reset Flash instruction (see Table 8). The microcontroller can
read the memory contents of main Flash or secondary Flash by using read operations any
time the read operation is not part of an instruction sequence.
188.8.131.52.2 Read the Main Flash Memory Identifier
The main Flash memory identifier is read with an instruction composed of 4 operations:
3 specific write operations and a read operation (see Table 8). The PSD835G2 main Flash
memory ID is E8h.
184.108.40.206.3 Read the Flash Memory Sector Protection Status
The Flash memory sector protection status is read with an instruction composed of 4
operations: 3 specific write operations and a read operation (see Table 8). The read
operation will produce 01h if the Flash sector is protected, or 00h if the sector is not
The sector protection status for all NVM blocks (main Flash or secondary Flash) can also
be read by the microcontroller accessing the Flash Protection and Flash Boot Protection
registers in PSD I/O space. See section 220.127.116.11.1 for register definitions.
18.104.22.168.4 Read the Erase/Program Status Bits
The PSD835G2 provides several status bits to be used by the microcontroller to confirm
the completion of an erase or programming instruction of Flash memory. These status bits
minimize the time that the microcontroller spends performing these tasks and are defined
in Table 9. The status bits can be read as many times as needed.
Table 9. Status Bits
CSBOOTi DQ7 DQ6 DQ5 DQ4 DQ3 DQ2 DQ1 DQ0
Data Toggle Error
VIH Polling Flag Flag
X Time- X
NOTES: 1. X = Not guaranteed value, can be read either 1 or 0.
2. DQ7-DQ0 represent the Data Bus bits, D7-D0.
3. FSi/CSBOOTi are active high.
For Flash memory, the microcontroller can perform a read operation to obtain these status
bits while an erase or program instruction is being executed by the embedded algorithm.
See section 22.214.171.124 for details.
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