pythonpython-requestsesp32micropython

How to do a get request in Micropython on ESP32?

I'm trying to do a simple get request with Micropython on an ESP32. Unfortunately I keep getting OSError: -202.

That's what I have so far:

wlan.py

import network

wlan = network.WLAN(network.STA_IF) # create station interface
wlan.active(True)       # activate the interface
wlan.connect('Schmittli', 'the key') # connect to an AP
wlan.ifconfig()         # get the interface's IP/netmask/gw/DNS addresses

And this is the REPL output:

>>> import wlan
import wlan
I (19080) wifi:wifi driver task: 3ffd1058, prio:23, stack:3584, core=0
I (38466) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
I (38466) system_api: Base MAC address is not set, read default base MAC address from BLK0 of EFUSE
I (38506) wifi:wifi firmware version: 44aa95c
I (38506) wifi:config NVS flash: enabled
I (38506) wifi:config nano formating: disabled
I (38506) wifi:Init dynamic tx buffer num: 32
I (38506) wifi:Init data frame dynamic rx buffer num: 32
I (38516) wifi:Init management frame dynamic rx buffer num: 32
I (38516) wifi:Init management short buffer num: 32
I (38526) wifi:Init static rx buffer size: 1600
I (38526) wifi:Init static rx buffer num: 10
I (38536) wifi:Init dynamic rx buffer num: 32
W (38536) phy_init: failed to load RF calibration data (0x1102), falling back to full calibration
I (38676) phy: phy_version: 4180, cb3948e, Sep 12 2019, 16:39:13, 0, 2
I (38696) wifi:mode : sta (30:ae:a4:f6:0f:08)
I (38696) wifi: STA_START
>>> I (38816) wifi:new:<1,0>, old:<1,0>, ap:<255,255>, sta:<1,0>, prof:1
I (39666) wifi:state: init -> auth (b0)
I (39676) wifi:state: auth -> assoc (0)
I (39686) wifi:state: assoc -> run (10)
I (39706) wifi:connected with Schmittli, aid = 28, channel 1, BW20, bssid = a0:b5:49:00:c6:cd
I (39706) wifi:security type: 3, phy: bgn, rssi: -53
I (39706) wifi:pm start, type: 1

I (39716) network: CONNECTED
I (39776) wifi:AP's beacon interval = 102400 us, DTIM period = 3
I (42456) event: sta ip: 192.168.1.118, mask: 255.255.255.0, gw: 192.168.1.1
I (42456) network: GOT_IP


>>> import urequests
import urequests
I (72686) modsocket: Initializing
>>> response = urequests.get('http://jsonplaceholder.typicode.com/albums/1')
response = urequests.get('http://jsonplaceholder.typicode.com/albums/1')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "urequests.py", line 108, in get
  File "urequests.py", line 53, in request
OSError: -202

I tried with two different ESP32 boards, so I don't think this is not a hardware problem. And yes, the URL works fine in my browser.

Update

Requesting the same service with it's IP address works. So it's a DNS Problem. I have 10+ diffrent devices on the same WLAN. All are working fine. So I really think this is a Mircopython problem.

This is the configuration, after the ESP32 connects to the WLAN:

>>> wlan.ifconfig()
wlan.ifconfig()
('192.168.1.116', '255.255.255.0', '192.168.1.1', '42.2.18.11')

In all my other devices the DNS server is '192.168.1.1'. I tried to set the DNS server manually in the ESP32, but that does not work:

>>> wlan.ifconfig('192.168.1.116', '255.255.255.0', '192.168.1.1', '192.168.1.1')
wlan.ifconfig('192.168.1.116', '255.255.255.0', '192.168.1.1', '192.168.1.1')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: function expected at most 2 arguments, got 5
>>> wlan.status()

Any ideas?

Solution

  • It looks like you DNS server is not resolving the fqdn to an IP address for some reason.

    import socket
print(socket.getaddrinfo('micropython.org', 80))
print(socket.getaddrinfo('jsonplaceholder.typicode.com', 80))
# sample return
[(2, 1, 0, 'micropython.org', ('176.58.119.26', 80))]
[(2, 1, 0, 'jsonplaceholder.typicode.com', ('104.27.188.192', 80))]

    If it is not your name resolution, you might be hitting a firewall.