#+TITLE: MicroPython Implementation Notes

* Backup Up firmware, flashing, etc.

On lolin32, need to hold down the reset while esptool is connecting,
and then release to get this to work.

** Backup existing firmware from 4M Flash ESP32
#+BEGIN_SRC bash
esptool.py -b 115200 --port /dev/ttyUSB0 read_flash 0x00000 0x400000 lolin32_original.bin
#+END_SRC

** Update Flash from backup
#+BEGIN_SRC bash
esptool.py -b 115200 --port /dev/ttyUSB0 write_flash --flash_freq 80m 0x000000 lolin32_original.bin
#+END_SRC

** Erase Flash
#+BEGIN_SRC bash
esptool.py -b115200  --port /dev/ttyUSB0 erase_flash
#+END_SRC

** Flash with MicroPython

#+BEGIN_SRC bash
esptool.py --chip esp32 --port /dev/ttyUSB0 write_flash -z 0x1000 ~/Downloads/esp32-idf3-20200902-v1.13.bin
#+END_SRC


* Circuit Layout

| Pin | Used For      |
|  37 | SDA - MPU6050 |
|  36 | SCL - MPU6050 |
|     |               |


* SSD 1306

#+BEGIN_SRC python
from machine import I2C, Pin
import ssd1306

rst = Pin(16, Pin.OUT)
rst.value(1)
scl = Pin(15, Pin.OUT, Pin.PULL_UP)
sda = Pin(4, Pin.OUT, Pin.PULL_UP)
i2c = I2C(scl=scl, sda=sda, freq=450000)
oled = ssd1306.SSD1306_I2C(128, 64, i2c, addr=0x3c)

oled.fill(0)
oled.text('ESP32', 45, 5)
oled.text('MicroPython', 20, 20)
oled.show() 
#+END_SRC

* MPU 6050 

#+BEGIN_SRC python
from machine import I2C, Pin
from mpu6050 import accel

scl=Pin(36, Pin.OUT)
sda=Pin(37, Pin.OUT)
i2c = I2C(scl=scl, sda=sda, freq=450000)
a = accel(i2c)
a.get_values()
#+END_SRC


* Turn off MPU (through vext, also turns off screen)
#+BEGIN_SRC python
from machine import Pin

vext = Pin(21, Pin.OUT, Pin.PULL_HOLD)
vext.value(0) # Turns ON Vext
vext.value(1) # Turns OFF Vext
machine.deepsleep()
#+END_SRC

* Wifi Connection Example, outbound requests.

#+BEGIN_SRC python
import network
import machine
wlan = network.WLAN(network.STA_IF)
wlan.active(True)
binary_id = machine.unique_id()
hostname = 'timeular-{:02x}{:02x}{:02x}{:02x}'.format(binary_id[0],binary_id[1], binary_id[2], binary_id[3])
wlan.config(dhcp_hostname='timeular')
wlan.connect("Hart's",'D187wn644GeH')
wlan.if_config()
#+END_SRC

* Getting a Unique ID for this instance 

#+BEGIN_SRC python
import machine
binary_id=machine.unique_id()
hex_id = '{:02x}{:02x}{:02x}{:02x}'.format(binary_id[0],binary_id[1],binary_id[2],binary_id[3])
#+END_SRC

This can be used to append to e.g. the DHCP hostname to make it likely
to be unique.

* NTP

#+BEGIN_SRC python
import ntptime
ntptime.settime()
import machine
rtc = machine.RTC()
rtc.datetime()
#+END_SRC

* Web Server

#+BEGIN_SRC python
import picoweb
from network import WLAN, STA_IF

app = picoweb.WebApp('main')

@app.route("/")
def index(req,resp):
    yield from picoweb.start_response(resp)
    yield from resp.awrite("Hello world from picoweb running on the ESP32")
 
app.run(debug=True,host=WLAN(STA_IF).ifconfig()[0],port=80)
#+END_SRC

* Connections

Pin 23 ESP -> SDA MPU
Pin 19 ESP -> SCL MPU

MPU AD0 -> - Rail
MPU GND -> - Rail
MPU Vcc -> + RailArduino MPU 6050 Serial Monitor

ESP GND -> - Rail
ESP VEXT -> +Rail

* [3/8] Things to look at

 - [X] Can we turn off the MPU with VEXT Control? (ESP Pin 21).
 - [X] Connecting to WiFi - Client Mode
 - [ ] Connecting to WiFi - Direct Mode
 - [ ] BLE?
 - [X] NTP?
 - [ ] How to store the data appropriately - Flash/SqlLite, RTC memory?
 - [ ] How to retrieve data over WiFi
 - [ ] How to detect battery low
 - [[https://github.com/tayfunulu/WiFiManager][WiFiManager]]



#+BEGIN_SRC python

#+END_SRC