On NRF52 I've been using the jlink fake serial console. But since the RAK815 has the serial port hooked up we can switch back to that once the basics are working.
- DONE increase preamble length? - will break other clients? so all devices must update
- DONE enable BLE DFU somehow
- report appversion/hwversion in BLE
- use new LCD driver from screen.cpp. Still need to hook it to a subclass of (poorly named) OLEDDisplay, and override display() to stream bytes out to the screen.
- we need to enable the external tcxo for the sx1262 (on dio3)?
- figure out which regulator mode the sx1262 is operating in
- do initial power measurements, measure effects of more preamble bits, measure power management and confirm battery life
- set UICR.CUSTOMER to indicate board model & version
## Items to be 'feature complete'
- check datasheet about sx1262 temperature compensation
- enable brownout detection and watchdog
- stop polling for GPS characters, instead stay blocked on read in a thread
- figure out what the correct current limit should be for the sx1262, currently we just use the default 100
- put sx1262 in sleepmode when processor gets shutdown (or rebooted), ideally even for critical faults (to keep power draw low). repurpose deepsleep state for this.
- good power management tips: <https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/optimizing-power-on-nrf52-designs>
- call PMU set_ADC_CONV(0) during sleep, to stop reading PMU adcs and decrease current draw
- do final power measurements
- backport the common PMU API between AXP192 and PmuBQ25703A
- use the new buttons in the UX
- currently using soft device SD140, is that ideal?
- turn on the watchdog timer, require servicing from key application threads
- nrf52setup should call randomSeed(tbd)
- implement SYSTEMOFF behavior per <https://infocenter.nordicsemi.com/topic/ps_nrf52840/power.html?cp=4_0_0_4_2>
## Things to do 'someday'
Nice ideas worth considering someday...
- enable monitor mode debugging (need to use real jlink): <https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/monitor-mode-debugging-with-j-link-and-gdbeclipse>
- Improve efficiency of PeriodicTimer by only checking the next queued timer event, and carefully sorting based on schedule
- make a Mfg Controller and device under test classes as examples of custom app code for third party devs. Make a post about this. Use a custom payload type code. Have device under test send a broadcast with max hopcount of 0 for the 'mfgcontroller' payload type. mfg controller will read SNR and reply. DOT will declare failure/success and switch to the regular app screen.
- Currently we use Nordic's vendor ID, which is apparently okay: <https://devzone.nordicsemi.com/f/nordic-q-a/44014/using-nordic-vid-and-pid-for-nrf52840> and I just picked a PID of 0x4403
- Use NRF logger module (includes flash logging etc...) instead of DEBUG_MSG
- Use "LED softblink" library on NRF52 to do nice pretty "breathing" LEDs. Don't whack LED from main thread anymore.
- decrease BLE xmit power "At 0dBm with the DC/DC on, the nRF52832 transmitter draws 5.3mA. Increasing the TX power to +4dBm adds only 2.2mA. Decreasing it to -40 dBm saves only 2.6mA."
- in addition to the main CPU watchdog, use the PMU watchdog as a really big emergency hammer
- turn on 'shipping mode' in the PMU when device is 'off' - to cut battery draw to essentially zero
- make Lorro_BQ25703A read/write operations atomic, current version could let other threads sneak in (once we start using threads)
- make the segger logbuffer larger, move it to RAM that is preserved across reboots and support reading it out at runtime (to allow full log messages to be included in crash reports). Share this code with ESP32 (use GCC noinit attribute)
- consider using "SYSTEMOFF" deep sleep mode, without RAM retention. Only useful for 'truly off - wake only by button press' only saves 1.5uA vs SYSTEMON. (SYSTEMON only costs 1.5uA). Possibly put PMU into shipping mode?
- change the BLE protocol to be more symmetric. Have the phone _also_ host a GATT service which receives writes to
'fromradio'. This would allow removing the 'fromnum' mailbox/notify scheme of the current approach and decrease the number of packet handoffs when a packet is received.
- Using the preceding, make a generalized 'nRF52/ESP32 BLE to internet' bridge service. To let nRF52 apps do MQTT/UDP/HTTP POST/HTTP GET operations to web services.
- lower advertise interval to save power, lower BLE transmit power to save power
- the SX126x class does SPI transfers on a byte by byte basis, which is very inefficient. Much better to do block writes/reads.
- To make Segger JLink more reliable, turn off its fake filesystem. "JLinkExe MSDDisable" per <https://learn.adafruit.com/circuitpython-on-the-nrf52/nrf52840-bootloader>
## Done
- DONE add "DFU trigger library" to application load
- DONE: using this: Possibly use this bootloader? <https://github.com/adafruit/Adafruit_nRF52_Bootloader>
- DONE select and install a bootloader (adafruit)
- DONE get old radio driver working on NRF52
- DONE basic test of BLE
- DONE get a debug 'serial' console working via the ICE passthrough feature
- DONE switch to RadioLab? test it with current radio. <https://github.com/jgromes/RadioLib>
- at boot we are starting our message IDs at 1, rather we should start them at a random number. also, seed random based on timer. this could be the cause of our first message not seen bug.
- make a new boarddef with a variant.h file. Fix pins in that file. In particular (at least):
#define PIN_SPI_MISO (46)
#define PIN_SPI_MOSI (45)
#define PIN_SPI_SCK (47)
#define PIN_WIRE_SDA (26)
#define PIN_WIRE_SCL (27)
- customize the bootloader to use proper button bindings
- remove the MeshRadio wrapper - we don't need it anymore, just do everything in RadioInterface subclasses.
- DONE use SX126x::startReceiveDutyCycleAuto to save power by sleeping and briefly waking to check for preamble bits. Change xmit rules to have more preamble bits.
- scheduleOSCallback doesn't work yet - it is way too fast (causes rapid polling of busyTx, high power draw etc...)
- make a file system implementation (preferably one that can see the files the bootloader also sees) - preferably <https://github.com/adafruit/Adafruit_nRF52_Arduino/blob/master/libraries/InternalFileSytem/examples/Internal_ReadWrite/Internal_ReadWrite.ino> else use <https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.3.0/lib_fds_usage.html?cp=7_5_0_3_55_3>
Good LED BLE demo [Here](https://github.com/adafruit/Adafruit_nRF52_Arduino/blob/master/libraries/Bluefruit52Lib/examples/Peripheral/nrf_blinky/nrf_blinky.ino)