innomatic

Most of the development kits from ST are equipped with on-board STLink-V2 debugger / programmers, use of which is not very convenient in Linux environment. Instead, Segger kindly provides a tool that allows you to reflash on-board STLink into JLink . Process takes only seconds. And you can enjoy most of the great features of JLink with no cost at least for STM32 devices. It keeps the UART port function, so you can use it as a serial monitor in addition to the JLink. If you have a Nucleo-64 board handy, you can make a nice stand-alone JLink debugger by reflashing the on-board STLink and snap it off. Note that the original pin headers are removed and some of them are replaced with right-angle type for the convenience. Two of the pins of ST-Link jumper are used to provide 3.3V power. And TX and RX pins of UART are soldered at the back not to interfere with the debug pins. Note the small changes in the solder bridges SB3 through SB10. Basically this allows the 3V3 line to b...

USB Mass Storage Class framework implements bulk-only-transfer (BOT) with SCSI protocol. USB packets from the host eventually converted SCSI transport commands by the middleware, in which data is exchanged (read / write) in the unit of logical block, typically 512 bytes. This SCSI commands works well with SD card system where a dedicated controller does the job of managing the actual memory elements. If you want to use a FLASH chip as a memory unit instead, you need to handle read / write operation directly. Fortunately, most of flash memory support 4KB block erase. This makes the 4096 bytes as a natural choice for the size of the logical block in the file usbd_storage_if.c. In this case, 8Mbit Flash memory was used. During initial enumeration, this information is registered to the host. The middleware maintains one logical block size of buffer and handles USB transaction where each payload is only 64 bytes. It then calls SCSI requests to store / retrieve data to / from physical...

Some of STM32 MCUs are equipped with TSC (Touch Sensing Controller), whose hardware performance is not bad compared to ASIC solutions. It is a self-sufficient module supporting multi-touch. And you can lower the power consumption down to few tens of micro amps. Setting up the TSC requires to select one port for sampling for each group. One group consists of one sampling channel, where a sampling capacitor is connected, with one or more measurement channel, where a sensor pad is connected. Charge transfer happens from a measurement channel to the sampling channel. This is done independently from other groups. Thus channels belongs to each group are measured at the same time. In the same group, however measurement should be done sequentially among channels. A PCB touch panel (on the right) is connected to a STM32L052 MCU. The MCU is programmed to measure the touch sensor value at every 100 msec. It transfers the measurement to a PC via UART connection. On the PC side, a py...

In this post, actual pushbutton checking algorithm is explained. As discussed previously, it utilizes the software timer (UsrTimer) to address the chattering issue and to implement a multi-function input button. The main timer routine is registered by calling: Source file 103 // initialize the pushbutton handler with mask byte. 104 PushButton_Init ( 0x01 ); where the mask byte (0x01) indicates the location of the state bits of active buttons in the 8bit button state byte. Here we have only one button that is located at the first bit location. This call starts a timer routine that runs indefinitely at a predefined interval, PUSHBTN_TMR_PERIOD whose value is set to 80 msec at the moment. This period can be tuned to serve particular hardware better. However you have to remember that other parameters such as the duration values that determine short click and long click have reference to this value. For example PUSHBTN_TO_SHORT value is set to 3, which means tha...

The Event Queue is a simple ring buffer, whose element is a byte array of fixed size. You can use it any purpose as long as it fits. When it is used as an event queue, the meaning of each byte is supposed to be defined by the user. In this example, we define the first byte as the event id followed by event data as below: Source file 73 /** Pushbutton input event 74 * 75 * Event Data: (PBTN_ID)(EVT_TYPE) 76 * 77 * * PBTN_ID: id of the pushbutton that generated the event 78 * * EVT_TYPE: type of the event such as single click, double click, 79 */ 80 #define EVT_PBTN_INPUT 0x10 ///< event code for pushbutton input 81 #define PBTN_SCLK 0x01 ///< single click 82 #define PBTN_LCLK 0x02 ///< long click 83 #define PBTN_DCLK 0x03 ///< double click 84 #define PBTN_TCLK 0x04 ///< triple click Posting an event is...

Project Design Pushbuttons, or tactile switches are convenient way of interacting with the firmware, whether the final product retains them as its UI components or not. There are a couple of things to consider to implement the pushbutton handling features. Debouncing and Software Timer First you have to deal with the contact bouncing effect of the switch.  Following snapshot of  an oscilloscope from Wikipedia page illustrates one situation. However it can be radically different from one case to another. There are numerous ways of addressing the issue, each of which has its own pros and cons. So one method works better in one situation but not necessarily in other cases primarily depending on the chattering characteristics but also depending on other situations. Here we are going to use software timer, in which a timer routine checks (samples) the state of the switch with a regular interval. Short Click vs. Long Click, Single Click vs. Multiple Click Another consi...

Most of the embedded projects share certain initial steps. You need to confirm the clock settings before doing anything, then you want to have debug connection via a UART channel since it is cheap  but still it can provide useful information for debugging. Let us start with CubeMX. You select a device/board of your choice, set up the pinouts for one GPIO output and one UART port. Configure the clock if necessary then create a project. Clock Checking using SysTick The sanity of the clock setting can be done by checking the SysTick interval. All Cortex-M series core have SysTick timer by default, which should fire at 1msec interval while the MCU is active. In the STM32Cube, the SysTick is initialized by HAL_Init() call, which in turn calls SysTick_Config() in CMSIS. Once the SysTick is initialized, it generates 1 msec interrupt and this interrupt is handled by SysTick_Handler() according to the Cube framework. Source file 1 /** 2 * @brief This function han...

The development environment discussed here is minimal, terminal based, and cross platform. This configuration assumes that a terminal based text editor such as vim  and the  make utility are the primary tools for programming. It consists of following components: GNU ARM Embedded Toolchain Makefile Utility STM32CubeMX Flash Tool (JLink or OpenOCD) Hardware The most recent version of the compiler suite can be found  here . The toolchain is self-sufficient. Thus you can simply unzip the archive into any directory of choice then you are good to go. In Linux, make  utility is included in a package such as  build-essential . If you have C/C++ compiler installed on your system then you already have it. In Windows, preferred way to get the utility is to install cygwin first, then to install make from there. Alternatively, you can use the one comes with MinGW system or you can find one of the precompiled version . However you may need to choose 32bi...