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Updated Persistent Memory (markdown)

euquiq 2020-06-04 01:37:12 -03:00
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Persistent-Memory.md

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This is a small amount of ram (only 256 bytes), part of the **RTC (Real Time Clock) subsystem**, inside the LPC43xx chip on the portapack hardware.
# RTC Subsystem # RTC Subsystem
The RTC subsystem also keeps the actual clock (date / time) running, powered by a CR2032 battery, (which needs to be installed on the portapack board!), even when the unit is not connected to an USB power source. The RTC subsystem also keeps the actual clock (date / time) running, powered by a CR2032 battery, (which needs to be installed on the portapack board!), even when the unit is not connected to an USB power source.
## backup_ram region This persistent memory is part of the **RTC (Real Time Clock) subsystem**, inside the LPC43xx chip on the portapack hardware.
The **backup_ram region** is defined in `/firmware/common/memory_map.hpp` and labeled as "LPC_BACKUP_REG_BASE" starting at address **0x40041000** If you are curious on how exactly the whole persistent memory is arranged, it's defined on `/firmware/chibios-portapack/os/hal/platforms/LPC43xx/lpc43xx.inc`:
If you are curious on how exactly these 256 bytes of persistent memory are arranged, it's defined on `/firmware/chibios-portapack/os/hal/platforms/LPC43xx/lpc43xx.inc`:
* **LPC_RTC_DOMAIN_BASE** (0x40040000) * **LPC_RTC_DOMAIN_BASE** (0x40040000)
* **LPC_ALARM_TIMER_BASE** (LPC_RTC_DOMAIN_BASE + 0x0000) * **LPC_ALARM_TIMER_BASE** (LPC_RTC_DOMAIN_BASE + 0x0000)
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* **LPC_OTP_CTRL_BASE** (LPC_RTC_DOMAIN_BASE + 0x5000) * **LPC_OTP_CTRL_BASE** (LPC_RTC_DOMAIN_BASE + 0x5000)
* **LPC_RTC_BASE** (LPC_RTC_DOMAIN_BASE + 0x6000) * **LPC_RTC_BASE** (LPC_RTC_DOMAIN_BASE + 0x6000)
## backup_ram region
The **backup_ram region** is a small amount of ram (only 256 bytes), defined in `/firmware/common/memory_map.hpp` and labeled as "LPC_BACKUP_REG_BASE" starting at address **0x40041000**
### data_t struct ### data_t struct
The Portapack firmware uses the backup_ram region to store several uint32_t (and one uint64_t) variables, inside a struct, called "data_t", declared on /firmware/common/portapack_persistent_memory.cpp The Portapack firmware uses the backup_ram region to store several uint32_t (and one uint64_t) variables, inside a struct, called "data_t", declared on /firmware/common/portapack_persistent_memory.cpp