When setting up Debian Linux (Bullseye) on my Lenovo IdeaCentre K430 computer, I encountered problems related to UEFI. After the installation, the system did not boot and displayed the message Error 1962: No operating system found. It took three attempts before I found the solution, which I describe here. First, ensure that UEFI is enabled …
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In Debian Linux, when a network interface is configured to obtain an IP address automatically, the DHCP client utility writes the values received from the server over the content of file /etc/resolv.conf. Thus, custom entries that you had saved in this file, typically domain suffixes and domain name servers, are lost. If you need DHCP …
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Throughout my technological lifetime I followed the convention that 1 kB was equal to 1000 bytes and that 1 KB was equal to 1024 bytes. Similarly, 1 mB was 1 000 000 bytes, and 1 MB was 1 048 576 bytes. In dial-up Internet days, we surmised that a 56K modem transferred data at a …
From man gmtime: The gmtime() function converts the calendar time timep to broken-down time representation, expressed in Coordinated Universal Time (UTC). It may return NULL when the year does not fit into an integer. The return value points to a statically allocated struct which might be overwritten by subsequent calls to any of the date …
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For WPS to work on the ESP8266 and using the non-OS SDK, be sure to call wifi_wps_enable() before setting the callback function with wifi_set_wps_cb(). For example: In the callback itself, call wifi_wps_disable() before wifi_station_connect(). For example:
If esptool is limited to 115200 bps when flashing your firmware to an ESP8266, you can try to increase the bitrate by following the steps below. Locate esptool.py for your installation. On Debian and Ubuntu, this file is located in /usr/share/esptool. Edit esptool.py and change the value on the line starting with ESP_ROM_BAUD from 115200 …
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I don’t remember if this information is in the documentation, but having spent a few hours to figure things out, I think it is important to record it here. For example:
On the ESP8266 ESP-01, CH_PD must be pulled HIGH at boot for the chip to work. A 10K resistor can be used for the pull-up. Some variants of the ESP-01 module already have CH_PD in the HIGH state.
I want to share an anecdote of confusing programming language features as a caution to my fellow programmers. Reviewing our application logs, I noticed that the API requests were interspersed with pauses of irregular durations. The interval between each successful request is supposed to be fixed; and the interval between each failed request, exponentially growing …
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A VARCHAR value that is in scientific notation can be converted to a DECIMAL value by first converting it to a REAL value, then to the DECIMAL value. For example: This also works with CAST.