FRAM ECC
302
SLAU367P – October 2012 – Revised April 2020
Copyright © 2012–2020, Texas Instruments Incorporated
FRAM Controller A (FRCTL_A)
8.3
FRAM ECC
FRAM ECC supports bit error correction and uncorrectable bit error detection.
Correctable errors are generally single-bit errors that are detected and corrected by the hardware, so they
do not result in data corruption or system failure. The CBDIFG FRAM correctable bit error flag is set if a
correctable bit error has been detected and corrected. CBDIE can be used to enable an NMI event.
Uncorrectable bit errors are always multiple-bit errors, and they indicate memory corruption. The UBDIFG
FRAM uncorrectable bit error flag is set if an uncorrectable bit error has been detected in the FRAM error
detection logic. UBDRSTEN can be used to enable a power up clear (PUC) reset, or UBDIE can be used
to enable an NMI event. UBDRSTEN and UBDIE are mutually exclusive and are not allowed to be set
simultaneously.
For more information, refer to the
MSP430 FRAM Quality and Reliability
application report.
8.4
FRAM Power Control
To achieve maximum power efficiency of FRAM operations, the FRAM controller A (FRCTL_A) supports a
power control mode. There are three inputs that influence the power state of FRAM: the FRPWR bit,
FRAM access (read or write), and the device power mode.
summarizes how FRAM power modes are controlled by the source.
shows the flow
of FRAM power mode transitions.
While the device is in active mode(AM), FRAM power is controlled by the FRPWR bit and FRAM access.
When the FRPWR is set, FRAM goes to ACTIVE mode regardless of FRAM access. When the FRPWR is
cleared by the CPU and there is no access to FRAM, the FRAM goes into INACTIVE mode so that the
FRAM does not consume power.
INACTIVE mode can be used if FRAM access is not required for a significant amount of time. For
example, short tasks can be executed from RAM, so while CPU runs from RAM, FRAM can be powered
off. When the FRAM is in the INACTIVE mode, wake-up is automatic. An access to FRAM (read or write)
wakes up the FRAM before performing the access. In this case, the FRPWR bit is set automatically by the
FRAM controller A (FRCTL_A).
Care must be taken when using the FRPWR bit. When the FRAM is powered off, there is a wake-up time
delay before the FRAM can be accessed again. The delay should be considered to avoid affecting system
performance. See the device data sheet for the delay time.
When the device enters LPM0, LPM1, LPM2, LPM3, or LPM4, the FRAM also enters INACTIVE mode
regardless of FRPWR bit status, however FRPWR bit determines the power status when the device
wakes up from a LPM. When the device wakes up from a low-power mode to active mode (AM), FRAM
Controller A (FRCTL_A) immediately wakes up FRAM memory if the FRPWR is set. If the FRPWR bit is
cleared, FRAM memory remains in INACTIVE mode until an access to FRAM occurs (read or write). The
latter case can be used to reduce the device power consumption if the device wakes up only for a short
amount of time, and the task during device active mode can be executed from RAM with no need to
access FRAM memory. See
and
for details.
Table 8-2. FRAM Power Mode Transition
Power Control Source
FRAM Power State
(Start)
FRAM Power State
(End)
Device Power Mode
FRPWR Bit
FRAM Access
AM
1 (after PUC)
Don't care
ACTIVE
ACTIVE
AM
1
→
0
No
ACTIVE
INACTIVE
AM
0
No
→
Yes
INACTIVE
ACTIVE (FRPWR bit is
set automatically)
AM
0
→
1
No
INACTIVE
ACTIVE
AM
→
LPM0, LPM1,
LPM2, LPM3, or LPM4
Don't care
No
Don't care
INACTIVE
LPM0
Don't care
No
→
Yes
Don't care
ACTIVE (FRPWR bit is
set automatically)