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TMS28F200BZT, TMS28F200BZB
262144 BY 8-BIT/131072 BY 16-BIT
BOOT-BLOCK FLASH MEMORIES
SMJS200E – JUNE 1994 – REVISED JANUARY 1998
6
POST OFFICE BOX 1443 • HOUSTON, TEXAS 77251–1443
command definition
Once a specific command code has been entered, the WSM executes an internal algorithm generating the
necessary timing signals to program, erase, and verify data. See Table 2 for the CSM command definitions and
data for each of the bus cycles.
Following the read-algorithm-selection-code command, two read cycles are required to access the
manufacturer-equivalent code and the device-equivalent code. The codes are shown in Table 4 and Table 5.
Table 2. Command Definitions
BUS
FIRST BUS CYCLE SECOND BUS CYCLE
COMMAND
CYCLES
REQUIRED
OPERATION ADDRESS
CSM
INPUT
OPERATION ADDRESS
DATA
IN/OUT
Read Operations
Read Array 1 Write X FFh Read X Data Out
Read Algorithm-Selection Code 3 Write X 90h Read A0 M/D
Read Status Register 2 Write X 70h Read X SRB
Clear Status Register 1 Write X 50h
Program Mode
Program Setup/ Program
(byte/word)
2 Write PA 40h or 10h Write PA PD
Erase Operations
Block-Erase Setup/
Block-Erase Confirm
2 Write BEA 20h Write BEA D0h
Erase-Suspend/
Erase-Resume
2 Write X B0h Write X D0h
Legend:
BEA Block-erase address. Any address selected within a block selects that block for erasure.
M/D Manufacturer-equivalent/device-equivalent code (see Table 4 and Table 5 for these codes).
PA Address to be programmed
PD Data to be programmed at PA
SRB Status-register data byte that can be found on DQ0–DQ7
X Don’t care
status register
The status register allows the user to determine whether the state of a program/erase operation is pending or
complete. The status register is monitored by writing a read-status command to the CSM and reading the
resulting status code on I/O pins DQ0–DQ7. This is valid for operation in either the byte- or word-wide mode.
When writing to the CSM in word-wide mode, the high order I/Os (DQ8–DQ15) can be set to any valid 2-state
level. When reading the status bits during word-wide read operation, the high order I/Os (DQ8–DQ15) are set
to 00h internally so the user only needs to interpret the low order I/Os (D0–DQ7).
After a read-status command has been given, the data appearing on DQ0–DQ7 remains as status-register data
until a new command is issued to the CSM. To return the device to other modes of operation, a new command
must be issued to the CSM.
Register data is updated on the falling edge of G
or E. The latest falling edge of either of these two signals
updates the latch within a given read cycle. Latching the data prevents errors from occurring should the register
input change during a status-register read. To assure that the status-register output contains updated status
data, E
or G must be toggled for each subsequent status read.
The status register provides the internal state of the WSM to the external microprocessor. During periods when
the WSM is active, the status register can be polled to determine the WSM status. Table 3 defines the
status-register bits and their functions.