PCB Connections

Device	Pin	Name	Name	Pin	Device	Notes
ESP32	10	IO25	TXD	9	SIM7070E	Modem to ESP, via Q7
ESP32	11	IO26	RXD	10	SIM7070E	ESP to Modem, via Q8
ESP32	6	IO34	RI	4	SIM7070E	Modem to ESP, SMS notification
ESP32	?	?	DTR	3	SIM7070E	ESP to Modem, via Q5
ESP32	12	IO27	PWRKEY	1	SIM7070E
n/a	n/a	n/a	PWRON	6	SIM7070E	connected to VD_EXT of SIM7070
ESP32	IO35	7	n/a	RS232-TX	External	detect when to power-on modem
ESP32	IO2	24	n/a	n/a	LED	On board LED
ESP32	36	IO22	SCL	4	IN219A	I2C bus
ESP32	33	IO21	SDA	3	IN219A	I2C bus

Modem Connection

Modem to ESP32 connection uses

from machine import Pin, UART, SoftI2C
import time

pwrkey = Pin(27, Pin.OUT, value=1)
tx = Pin(26, Pin.OUT)
rx = Pin(25, Pin.IN)
uart = UART(1, tx=tx, rx=rx, baudrate=9600, timeout=50)
pwrkey.value(0)
time.sleep(2)
pwrkey.value(1)
time.sleep(2)
l = uart.read()
if l:
    print(l)

uart.write("\n\nAT\n\n")
for _ in range(5):
    l = uart.read()
    if l: print(l)

External modem connection

ext = Pin(17, Pin.OUT, value=0)
# to turn Teltonika modem on, set value to 1
ext.value(1)

# to turn Teltonika modem on, set value to 1
ext.value(0)

LED

led = Pin(2, Pin.OUT, value=0)
led.value(1)
led.value(0)

Battery Monitor

IN219A - possible Micropython library at

from machine import Pin, UART, SoftI2C
from ina219 import INA219
import time

i2c = SoftI2C(freq=100000, scl=Pin(22, Pin.OUT), sda=Pin(21, Pin.OUT))
i2c.scan()
# response is [64]

ina = INA219(0.1, i2c)
# 0.1 is shunt resistance
print(ina.voltage())