MOTOROLA
Chapter 21. CDR3 Flash (UC3F) EEPROM
21-27
UC3F Operation
lowermost addresses are used to encode words that get programmed in the shadow row. The
shadow information is physically located in lowest numbered block and will also be located
in small block 0 if the lowest numbered block hosts a small block in the implemented
configuration.
21.3.7.3 Program Suspend
The program operation may be suspended to allow read accesses to the array. Setting the
HSUS bit in the UC3FCTL to a 1 while PE = 0, EHV = 1, and HVS = 1 forces the array
into a program suspend state. The deassertion of the HVS bit (HVS = 0) signifies that the
program operation has been successfully suspended. The HVS bit should negate within
10
s of asserting the HSUS bit.
While in program suspend mode, normal read accesses may be performed to the UC3F
array or shadow information words. Reads to the array location targeted for program return
indeterminate data since only a partial programming operation may have been performed.
The program operation may be resumed by setting HSUS = 0.
NOTE
Repeated suspending of a program operation to fetch array
contents may extend the program operation. The internal
program hardware may only resume the program operation at
predefined steps of the internal program hardware sequence;
interrupting the program operation on a high frequency basis
may cause the internal program hardware to delay completion
of the current step and delay advancement to the next step of
the
internal
program
hardware
sequence.
Frequent
suspend/resume operations (more than approximately once per
millisecond) may also cause program or erase timeouts, and are
not recommended.
21.3.8
Erasing
To modify the charge stored in an isolated element of the UC3F bit from a logic 0 state to
a logic 1 state, an erase operation is required. In the UC3F EEPROM, erase is a bulk
operatBlockion that affects the stored charge of all the isolated elements in an array block.
To make the UC3F module block-erasable, the array is divided into blocks that are
physically isolated from each other. Each of the array blocks may be erased in isolation or
in any combination. The UC3F array block size is fixed for all blocks in the module at 64
Kbytes and the module is comprised of eight blocks. Two of these blocks may be further
subdivided into two small blocks. Array blocks of the UC3F EEPROM that are protected
(PROTECT[M] = 1 or (SBEN[M] = 1 & SBPROTECT[M] = 1)) will not be erased. Also,