# Configuration persistence, non-volatile flash, BBR. (timing breakout)

**URL:** <https://community.sparkfun.com/t/configuration-persistence-non-volatile-flash-bbr-timing-breakout/68921>\
**Category:** GPS/GNSS\
**Created:** [May 30, 2026, 7:02pm UTC](https://community.sparkfun.com/t/configuration-persistence-non-volatile-flash-bbr-timing-breakout/68921 "2026-05-30T19:02:57Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![PulsePerSec](https://avatars.discourse-cdn.com/v4/letter/p/a587f6/32.png) [@PulsePerSec](https://community.sparkfun.com/u/PulsePerSec)\
**Post date:** [May 30, 2026, 7:02pm UTC](https://community.sparkfun.com/t/configuration-persistence-non-volatile-flash-bbr-timing-breakout/68921/1 "2026-05-30T19:02:57Z")

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regarding,

```auto
SparkFun GNSS Timing Breakout - ZED-F9T (Qwiic)
SKU: GPS-18774

```

We must modify some configuration items, as well as a dozen or so other ones not shown (CFG-TP-FREQ\_TP1 , CFG-TP-FREQ\_LOCK\_TP1, CFG-TP-PULSE\_LENGTH\_DEF,CFG-TP-LEN\_LOCK\_TP1,CFG-TP-POL\_TP1,CFG-TP-TP1\_ENA) These configuration changes are expected to persist between power cycles of the board.

Is this retention of config only possible using the BBR ? Or can these changes to settings be permanently modified by somehow backing them up to non-volatile flash?

(If BBR is the only option here, what is the expected retention time of the small rechargeable coin battery? Documentation is inconsistent and some claim 24 hours while others claim weeks.)

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<div class="post-metadata">

**Author:** ![PaulZC](https://yyz1.discourse-cdn.com/sparkfun/user_avatar/community.sparkfun.com/paulzc/32/67_2.png) [@PaulZC](https://community.sparkfun.com/u/PaulZC)\
**Post date:** [June 1, 2026, 6:13am UTC](https://community.sparkfun.com/t/configuration-persistence-non-volatile-flash-bbr-timing-breakout/68921/2 "2026-06-01T06:13:20Z")

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Hi @PulsePerSec ,

The ZED-F9T supports both external battery-backed-RAM and internal flash. You can write the pulse configuration to flash memory using the CFG-VALSET `layers` bitfield. Set `layers` to 7 to set the configuration in RAM + BBR + Flash. Please consult the [interface description](https://cdn.sparkfun.com/assets/3/f/2/3/3/ZED-F9T_InterfaceDescription.pdf) for more details.

I hope this helps,  
Paul