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Updated Persistent Memory (markdown)

euquiq 2020-06-04 01:27:36 -03:00
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Persistent-Memory.md

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All configuration parameters are stored as uint32_t and int64_t variables inside **data_t Struct** declared on `/firmware/common/portapack_persistent_memory.cpp`
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.
## data_t struct
# RTC Subsystem
The data_t struct persists inside a **backup_ram region** defined in `/firmware/common/memory_map.hpp`
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 portapack is not connected to an USB power source.
## backup_ram region
The **backup_ram region** address is defined in `/firmware/common/memory_map.hpp`, starting at **0x40041000**
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`:
```#define LPC_RTC_DOMAIN_BASE (0x40040000)`
#define LPC_ALARM_TIMER_BASE (LPC_RTC_DOMAIN_BASE + 0x0000)
#define LPC_BACKUP_REG_BASE (LPC_RTC_DOMAIN_BASE + 0x1000)
#define LPC_POWER_MODE_CTRL_BASE (LPC_RTC_DOMAIN_BASE + 0x2000)
#define LPC_CREG_BASE (LPC_RTC_DOMAIN_BASE + 0x3000)
#define LPC_EVENT_ROUTER_BASE (LPC_RTC_DOMAIN_BASE + 0x4000)
#define LPC_OTP_CTRL_BASE (LPC_RTC_DOMAIN_BASE + 0x5000)
#define LPC_RTC_BASE (LPC_RTC_DOMAIN_BASE + 0x6000)```
### 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
### Variables stored in persistent memory
Found in **original portapack**, but only carrying a few configuration variables, it was later expanded by furrtek's **HAVOC** version, incorporating several new configuration parameters.