P30
Before issuing a new command, the Status Register contents should be examined and
then cleared using the Clear Status Register command. Any valid command can follow,
when word programming has completed.
11.1.1
Factory Word Programming
Factory word programming is similar to word programming in that it uses the same
commands and programming algorithms. However, factory word programming
enhances the programming performance with VPP = VPPH. This can enable faster
programming times during OEM manufacturing processes. Factory word programming
is not intended for extended use. See Section 5.2, “Operating Conditions” on page 25
for limitations when VPP = VPPH
.
Note: When VPP = VPPL, the device draws programming current from the VCC supply. If VPP is driven
by a logic signal, VPPL must remain above VPPL MIN to program the device. When VPP = VPPH
,
the device draws programming current from the VPP supply. Figure 29, “Example VPP Supply
Connections” on page 61 shows examples of device power supply configurations.
11.2
Buffered Programming
The device features a 32-word buffer to enable optimum programming performance.
For Buffered Programming, data is first written to an on-chip write buffer. Then the
buffer data is programmed into the flash memory array in buffer-size increments. This
can improve system programming performance significantly over non-buffered
programming.
When the Buffered Programming Setup command is issued (see Section 9.2, “Device
Commands” on page 45), Status Register information is updated and reflects the
availability of the buffer. SR[7] indicates buffer availability: if set, the buffer is
available; if cleared, the buffer is not available. To retry, issue the Buffered
Programming Setup command again, and re-check SR[7]. When SR[7] is set, the
buffer is ready for loading. (see Figure 40, “Buffer Program Flowchart” on page 81).
On the next write, a word count is written to the device at the buffer address. This tells
the device how many data words will be written to the buffer, up to the maximum size
of the buffer.
On the next write, a device start address is given along with the first data to be written
to the flash memory array. Subsequent writes provide additional device addresses and
data. All data addresses must lie within the start address plus the word count.
Optimum programming performance and lower power usage are obtained by aligning
the starting address at the beginning of a 32-word boundary (A[4:0] = 0x00). Crossing
a 32-word boundary during programming will double the total programming time.
After the last data is written to the buffer, the Buffered Programming Confirm command
must be issued to the original block address. The WSM begins to program buffer
contents to the flash memory array. If a command other than the Buffered
Programming Confirm command is written to the device, a command sequence error
occurs and Status Register bits SR[7,5,4] are set. If an error occurs while writing to the
array, the device stops programming, and Status Register bits SR[7,4] are set,
indicating a programming failure.
When Buffered Programming has completed, additional buffer writes can be initiated by
issuing another Buffered Programming Setup command and repeating the buffered
program sequence. Buffered programming may be performed with VPP = VPPL or VPPH
(see Section 5.2, “Operating Conditions” on page 25 for limitations when operating the
device with VPP = VPPH).
November 2007
Order Number: 306666-11
Datasheet
57
NUMONYX [ NUMONYX B.V ]
