Display various signal or status properties in the form of a bar graph with JSB-R102510ZR and STM32F091RC

BarGraph Click is based on the JSB-R102510ZR, a bar graph LED array with ten red-colored LED segments from Ningbo, and two 74HC595, 8-bit serial-in, parallel-out shift registers with output latches from Texas Instruments to drive the JSB-R102510ZR. The 74HC595 ICs are comprised of a D-type internal storage register, as well as the serial-to-parallel shift register, both 8-bit wide. Each of these registers has its clock line, making it possible to clock in the desired data and then clock it out to the parallel output pins. The JSB-R102510ZR bar graph LED array has 10 red-colored LED segments. Each LED has its anode and cathode routed out, making each LED element absolutely independent so that it can be used in any circuit configuration. However, the JSB-R102510ZR bar graph display is connected as the display with the common cathode, meaning that all LED cathodes are connected to a single point. This LED cathode common line (CC) is connected to the drain of the N channel MOSFET, while its source is connected to the GND. Driving this MOSFET via its gate through the PWM pin of the mikroBUS™ allows dimming of the LED segments. Changing the PWM signal's duty cycle makes it possible to change the brightness of the XGURUGX10D bar graph display. The gate of this MOSFET is

connected to the PWM pin of the mikroBUS™ and it is pulled to VCC, allowing the display to work if the PWM pin is left floating. The Click board™ communicates with the host MCU via the mikroBUS™ SPI interface pins. Two bytes of information (16 bits in total) are pushed through the serial data input pin (DS) of the first 74HC595 IC, and routed to the SDI pin. The 74HC595 construction is such that after receiving 8 bits, clocking in one more bit will shift the existing 8 bits by one place, overflowing the last bit to the Q7S output pin and shifting it out that way. Since the Q7S of the first 74HC595 is connected to the DS pin of the second 74HC595, clocking 16 bits into the first 74HC595 IC will fill up both ICs with required data. Note that only two bits of the second byte will be used since the second shift register only has two outputs connected to the bar graph display (8 from the first IC + 2 from the second). It is worth mentioning that the Q7S of the last 74HC595 IC is routed to the MISO pin of the mikroBUS™, labeled as the SDO, allowing connection of multiple devices in cascade, building more complex setups. Adding more devices in the cascade would require more 8-bit words to be clocked into the first 74HC595 IC in the chain. When the data has been clocked in, the

SPI clock should be stopped, and the CS pin should be driven to a HIGH logic level. The CS pin of the mikroBUS™ is routed to the STCP pin of the 74HC595 ICs and labeled as LT on the Click board™. A rising edge on the STCP input pins of the 74HC595 ICs will latch the data from their internal storage registers to the output pins, polarizing the connected bar graph segment anodes. The onboard resistor pulls the STCP pin to a LOW logic level. If the previously mentioned MOSFET is in a conductive state, the current can flow through the LEDs, and the polarized LED elements will be lit. The #MR pin is used to clear the data in the internal storage register of the ICs. The LOW logic level on this pin will clear the content of this storage register, but it will not turn off the already activated outputs. The #MR pin is routed to the RST pin of the mikroBUS™, labeled as MR, and pulled to a HIGH logic level by the onboard resistor. 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.