Simplify data and information visualization with HCMS-3906 and STM32F091RC

Dot Matrix R Click is based on the HCMS-3906, a four-digit dot matrix display module from Broadcom. Dot Matrix R Click is a high-performance, easy-to-use dot matrix display driven by an onboard CMOS IC. Each display can be directly interfaced with a microprocessor, thus eliminating the need for cumbersome interface components. The serial IC interface allows higher character count information displays with a minimum of data lines. The easy-to-read 5x7 pixel format allows the display of upper case, lower case, Katakana, and custom user-defined characters. These displays are stackable in the x- and y-directions, making them ideal for high character count displays. Typical applications include telecommunication equipment, portable data entry devices, computer peripherals, medical equipment, test equipment, business machines, avionics, industrial controls, and more. Featured LED display HCMS-3906 consists of LEDs configured as 5x7 font characters driven in groups of 4 characters per IC. Each IC comprises a 160-bit shift register (the Dot Register), two 7-bit Control Words, and refresh circuitry. The Dot Register contents are mapped on a one-to-one basis to the display. Thus, an individual Dot Register bit uniquely controls a single LED. Reset initializes the Control Registers (sets all Control Register bits to

logic low) and places the display in sleep mode. The Dot Registers are not cleared upon power-on or by Reset. After power-on, the Dot Register contents are random; however, Reset will put the display in sleep mode, thereby blanking the LEDs. The Control Register and the Control Words are cleared to all zeros by Reset. Load the Dot Register with logic lows to operate the display after being Reset. Then, load Control Word 0 with the desired brightness level and set the sleep mode bit to logic high. The Dot Register holds the pattern to be displayed by the LEDs. First, RS is brought low, then CE is brought low. Next, each successive rising CLK edge will shift the data at the DIN pin. Loading a logic high will turn the corresponding LED on; a logic low turns the LED off. When all 160 bits have been loaded, CE is brought to logic high. When CLK is next brought to logic low, new data is latched into the display dot drivers. Loading data into the Dot Register occurs while the previous data is displayed and eliminates the need to blank the display while loading data. In a 4-character display, the 160 bits are arranged as 20 columns by 8 rows. This array can be conceptualized as four 5x8 dot matrix character locations, but only 7 of the 8 rows have LEDs. The bottom row (row 0) is not used. Thus, latch location 0 is never displayed. Column 0 controls the left-most column.

Data from Dot Latch locations 0-7 determine whether or not pixels in Column 0 are turned on or off. Therefore, the lower left pixel is turned on when a logic high is stored in Dot Latch location 1. Characters are loaded serially, with the left-most character loaded first and the rightmost character loaded last. By loading one character at a time and latching the data before loading the next character, the figures will appear to scroll from right to left. The Control Register allows software modification of the IC’s operation and consists of two independent 7-bit control words. Bit D7 in the shift register selects one of the two 7-bit control words. Control Word 0 performs pulse width modulation, pixel map, brightness control, peak pixel current brightness control, and sleep mode. Control Word 1 sets serial/simultaneous data out mode and external oscillator prescaler. Each function is independent of the others. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

Nucleo-64 with STM32F091RC MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin

headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is

provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.