Raspberry Pi Media Server: a Wifi routing Hotspot, Music server and client

Note:

• These Hotspot instructions relate only to the Pi 3B+ and Pi4 running on Stretch and Buster (Debian 9 and 10).
  
• The new Pi4 is much faster but the 'Buster' Linux Raspbian isn't quite the same yet in small but vital areas.
  
• The actual Seedeclip4 software will run on both without issue.
  

Music server on a wired ethernet

1. Install SeeDeClip4
   
2. Add your music files
   

Music server on a portable wireless hotspot (optional wired ethernet)

1. Setup the Pi3B+ or Pi4 as a WiFi hotspot with optional internet routing via ethernet
   There are many instructions about a dumb hotspot or a Wifi access point (bridge) but look here to find out how to have your own private, standalone Wifi hotspot that you can add internet access to simply by plugging in the ethernet.
   I.e. this is a wireless hotspot router, so you can surf the net while listening to music from your SeeDeClip4 server. Then you can unplug it and take it with you the car or campervan and use it as a hotspot music server there too.
   
2. Install SeeDeClip4
   
3. Add your music files
   

Music slave to drive a DAC via USB

1. Install runslave.sh (downloaded from SeeDeClip4 when running) and configure]
   

Cooling the Pi4

1. The heatsink can be any stickon Pi3 type heatsink.
   
2. The fan needs to be a 5V 30mm x 30mm x 7mm fan for the Pi
   

Then pins along the GPI can be used:

1. +5V
   
2. +5V (Connect to the +ve bit of the fan)
   
3. Gnd (Connect to the Source of an IRLZ44N MOSFET (or smaller compatible one)
   
4. GPIO14 (Connect to the Gate of the IRLZ44N)
   

Then connect the -ve (black) of the fan to the Drain of the IRLZ44N. Optionally connect a 100uF cap and IN4001 Diode in parallel with the fan, the cap +ve and diode bar toward the red +ve of the fan.

/usr/local/bin/pi4fan.py

import RPi.GPIO as GPIO import time # CPU temp? def get_cpu_temp():     tempc = 70     fin = open("/sys/class/thermal/thermal_zone0/temp", "r")     if (fin):         line = fin.readline()         fin.close()         try:             tempc = 0.001 * int(line)         except:             tempc = 75     return tempc # Calculate required PWM def calc_pwn(otemp):     pwm_min = 30     pwm_max = 100     temp_min = 45     temp_max = 60     temp = otemp     if (temp < temp_min):         temp = temp_min     elif (temp > temp_max):         temp = temp_max     ratio = (temp - temp_min) / (temp_max - temp_min)     pwm = pwm_min + ratio * (pwm_max - pwm_min)     desc = "Temp = %0.2fC, PWM = %0.2f%%" % (otemp, pwm)     fout = open("/tmp/faninfo.txt", "w")     if (fout):         fout.write(desc + "\n")         fout.close()     # print(desc)     return pwm # Run the PWM for the fan.. def fan_control():     pwm = 1     fan = 14     fifolen = 5     fifo = []     GPIO.setwarnings(False)     GPIO.setmode(GPIO.BCM)     GPIO.setup(fan, GPIO.OUT, initial=GPIO.LOW)     # Create a PWM     p = GPIO.PWM(fan, 40)     # Full blast to unstick!!     p.start(100)      time.sleep(1.5)     # Scan temperatures     f = 0     while (True):         time.sleep(1.0)         # Measure SOC         temp = get_cpu_temp()         # Fifo to smooth the fan speed changes         fifo.insert(0, temp)         count = len(fifo)         if (count > fifolen):             fifo.pop()             count -= 1         # Average temp         for i in range(1, count):             temp += fifo[i]         temp /= count         # Set it!         pwm  = calc_pwn(temp)         p.ChangeDutyCycle(pwm)  # where 0.0 <= pwm <= 100.0 fan_control()

(sleep 1 && /usr/bin/python /usr/local/bin/pi4fan.py ) &

{Pi4} cat /tmp/faninfo.txt Temp = 47.81C, PWM = 43.11% {Pi4}