Add nadhat_v1 board

draft/overlay/nadhat_v1.md

@@ -0,0 +1,56 @@
+<!--
+---
+name: NadHAT v1
+class: board
+type: IOT,ADC
+formfactor: pHAT
+manufacturer: Garatronic
+description: An GSM/GPRS add-on board for the Raspberry Pi
+url: https://www.garatronic.fr
+github: https://github.com/garatronic/nadhat
+schematic: https://github.com/garatronic/nadhat/tree/master/hardware/nadhat_v1_schematics.pdf
+buy: https://www.amazon.co.uk/NadHAT-GPRS-expansion-board-Raspberry/dp/B076M83F38
+image: 'nadhat_v1.png'
+pincount: 40
+eeprom: no
+power:
+  '2':
+ground:
+  '6':
+  '9':
+  '14':
+  '20':
+  '25':
+  '30':
+  '34':
+  '39':
+pin:
+  '8':
+    mode: uart
+    name: TXD
+  '10':
+    mode: uart
+    name: RXD
+  '37':
+    name: PWR_BT
+    mode: output
+    active: high
+-->
+# NadHAT v1
+
+NadHAT v1 is a GSM/GPRS modem pHAT for the Raspberry pi based on Simcom SIM800C standard module, gammu and pppd compatible for SMS and DATA exchange.
+
+It have a timekeeper with CR1225 coin cell, one 10 bits ADC channel, 2 status LEDS and an efficient switched mode DC/DC converter. It needs a micro sim card line suscriber to work with it.
+
+To install the necessary software, use the following commands:
+
+```bash
+sudo apt-get install minicom python-dev python-setuptools
+sudo apt-get install python-serial python-pip git
+sudo pip install wiringpi
+sudo apt-get install wiringpi
+cd ~
+git clone https://github.com/garatronic/nadhat
+cd nadhat/software
+./nadpwr.sh
+```