I am facing a problem while using bmp180 pressure sensor and BH1750 light intensity sensor.
I didn't find any way to configure both sensors with NodeMCU, as both have SDA and SCL pin and both can be pined with D1 and D2 only.
So where we can pin the SDA and SCL of BMP180 or BH1750 sensor other then D1 and D2 with NODEMCU
You could connect both devices on the same bus/pins, and they will be communicated via different addresses.
Usually I2C devices will have their unique addresses, e.g. BMP180 default I2C address is 0x77, while BH1750 default I2C address is 0x23.
You can also config address for the above devices, please refer to datasheets for details.
Related
What is the correct BPF filter for only recieving packets where the source MAC address is equal to the transmission MAC address?
Looking at the documentation, it seems like the fields should be available through either wlan[21:12] or wlan.addr2 but I'm unable to get those to work.
According to the pcap-filter manpage, capture filters for tshark or Wireshark don't support comparing packet fields against each other.
You can, however, do that with the display filter (top bar in Wireshark, once capture started):
wlan.sa == wlan.ta
To check whether the DS flag is equal to 0x1 using a capture filter, you can do the following:
wlan[1] & 3 = 1
It retrieves the second byte of the wlan header (wlan[1]), masks the 2 lower bits (& 3), and compares the result to 1.
how to use AT+CWLAP in esp8266 to get wifi signal strength? I want to get the signal strength which is displayed on the serial monitor and use it in my code in arduino IDE!
After sending the AT+CWLAP command, ESP8266 will answer with a list of all available AP's detected.
The format of the response will be like:
+CWLAP:<ecn>,<ssid>,<rssi>,<mac>,<freq offset,<freq calibration>
where:
<ecn>: indicates the security level, from 0 (OPEN) to 4 (Maximum security level)
<ssid>: it's the ssid of the AP
<rssi>: it's the signal strength, which is indicated in decibel format (e.g. -70)
<mac>: it's the MAC address
<ch>: channel
<freq offset>: ut's the frequency offset of AP，unit：KHz.
<freq calibration>: it's the calibration for frequency offset
So, the <rssi> parameter is what you are interested in.
Maybe, depending on the firmware version of your ESP8266, it's possible that AT+CWLAP command returns a different number of parameters, omitting, for example, the last four.
I use an ESP8266 dev board from NodeMCU with Lua. I power my chip with two AA batteries, which gives me 3V. See this:
https://www.hackster.io/noelportugal/ifttt-smart-button-e11841
How do I check the battery status using NodeMCU?
With a recent firmware you can use adc.readvdd33(). That should be enough for your case
I read somewhere that adc.readvdd33() was deprecated? Effectively it is for many of the ESP8266 modules available, the docs say, "If the ESP8266 has been configured to use the ADC for sampling the external pin, this function will always return 65535". So that means that any ESP8266 that has an ADC pin (like ESP8266-07 or -12, etc.) has this shunted in firmware.
But by adding a couple of resistors to make a voltage divider, you can still use the ADC pin for this.
[![schematics][1]][1]
[1]: http://i.stack.imgur.com/FEILF.png
Those resistor values will allow it to read 0-12V, as a value between 0-1024. (The voltage at the ADC pin must be less than 1V.)
val = adc.read(0)
Addendum: Adding this to your circuit incurs a power draw of approx. 0.01 milliamps, small but more than nothing. Multiply the values by 1000 to reduce it to infinitesimal. Or use 18 megaohm for r1 and 2 megaohm for r2, which divides the voltage by 10, and (wild guess) drains less current than most if not all batteries will attenuate when disconnected.
In other words, can a router have more than one BSSID (for example, implementing two different versions of the 802.11 protocol)?
And if so, are the RSSIs from the BSSIDs of a specific router exactly the same?
Yes ,you can have multiple BSSID on single router (or card) by making
Multile VAP(virtual access point)
But , the RSSI should always be same for all new VAPs as RSSI depend on
Tx Power (output power) ,thus can set one output power per chip (router).
you can change output power (RSSI) for different VAPs (BSSID) if it have more
than one Wlan Chip inside .
I am developing a handheld device based on IMX233 running embedded linux and is using Unifi CSR6026 for connecting to the WiFi networks. I have got the basic WiFi connectivity running using the wpa_supplicant and wpa_cli utilities. But i'm not able to detect when the user has entered a wrong key for the access point. The 'wpa_cli status' shows 'wpa_state=COMPLETED' and the iwconfig also returns the correct ESSID and MAC address of the access point as currently connected. Is there any other way to find out whether the user has entered a wrong key or not ??
root#freescale ~$ wpa_cli status
Selected interface 'eth0'
bssid=00:24:01:6a:3f:26
ssid=FirstFloorBGN
id=1
pairwise_cipher=WEP-40
group_cipher=WEP-40
key_mgmt=NONE
wpa_state=COMPLETED
root#freescale ~$ iwconfig
lo no wireless extensionsunifi1: unifi_giwencode: Surprise, do not have a
valid key index (0)
.
eth0 IEEE 802.11-b/g ESSID:"FirstFloorBGN"
Mode:Managed Frequency:2.422 GHz Access Point: 00:24:01:6A:3F:26
Bit Rate=24 Mb/s
RTS thr=0 B Fragment thr:off
Encryption key:off
Power Management period:500ms mode:All packets received
Link Quality=25/40 Signal level=-47 dBm Noise level=-72 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:0 Missed beacon:0
With WEP, there is no explicit key exchange, so there is no place in which a decryption error could be noticed. Your options are
switch to WPA
monitor the wireless statistics for decryption errors.
Note that the latter need not be an indication that the access point is using a different key.