Browsing All posts tagged under »tcp/ip«

Simple time synchronization for the Internet of Things

February 18, 2016


While adding HTTPS capabilities to my STM32 Nucleo board, I needed to solve the problem of current time. This is because TLS needs to check certificate expiration date, so we need a sufficiently accurate estimation of time. So I tried to understand what could I do to ask a network server about the time. I […]

HTTPS client on STM32 Nucleo-F411RE

February 4, 2016


One of my goal of the past months was to use an STM32 Nucleo board to get a webpage through HTTPS, using an Ethernet shield for TCP/IP stack. I was close last time, but I discovered that my Nucleo-F103RB did not have enough RAM. Now I have my hands on a Nucleo-F411RE that has 128KiB of RAM […]

STM32 NUCLEO-F103RB has low resources for TLS 1.2

January 10, 2016


It’s been months since I started playing with a STM32 Nucleo + Ethernet shield. One of the objectives that I chase is to build a device for the Internet of Things that implement reasonably secure communications. In an effort to avoid reinventing the wheel (or at least to not reinvent too many wheels) I wanted to see if […]

DHCP client on STM32 Nucleo and W5100

December 7, 2015


I am still working on a device consisting of STM32 Nucleo F103RB with a W5100 Ethernet shield. This time I included a DHCP client, so that when the device is attached to a network, it will ask for an IP address instead of being statically allocated. The DHCP protocol follows the RFC 2131 and RFC 2132, and […]

Update on POSIX socket library for W5100: client and server for TCP or UDP

November 22, 2015


I am writing a library that implements POSIX sockets, also called Berkeley sockets, for my ST Nucleo+Ethernet shield setup. The functionality that is currently in place, as for the source code on GitHub, allows for TCP client/server connections and UDP client/server communication using Wiznet W5100 chip resources. The interface is not complete, but what’s in place is taken as literally as I […]

Arduino Ethernet shield and Python socket

June 14, 2015


I started playing with an Ethernet shield for Arduino that I bought at a faire. I noticed that the shield itself is not original, but it’s a clone of the Arduino Ethernet Shield version 5.0, also identified as revision 2. The shield provides Ethernet connectivity and has an SD card slot to provide non-volatile memory […]