SPI 8-14 with MAX6954 Display Driver

This is a SPI 8-14 segment display board that John Monte designed for our company to use with the MAX6954 SPI display driver to help with the aid of developing products for our customers. The board can be used in multiple displays for a project.

John select a Microchip PIC chip to run the display board with, but it can be used with any microcontroller chip with an SPI connection. If you are interested in this type of display solution for your project please contact us.

The MAX6954 is a compact display driver that inter- faces microprocessors to a mix of 7-segment, 14-seg- ment, and 16-segment LED displays through an SPI-/ QSPI™-compatible 4-wire serial interface. The serial interface may be cascaded through multiple devices. The MAX6954 drives up to 16 digits 7-segment, 8 dig- its 14-segment, 8 digits 16-segment, or 128 discrete LEDs, while functioning from a supply voltage as low as

2.7V. The driver includes five I/O expander (or GPIO) lines, some or all of which may be configured as a key-switch reader, which automatically scans and debounces a matrix of up to 32 switches.

Included on chip are full 14- and 16-segment ASCII 104-character fonts, a hexadecimal font for 7-segment displays, multiplex scan circuitry, anode and cathode driv- ers, and static RAM that stores each digit. The maximum segment current for the display digits is set using a single external resistor. Digit intensity can be independently adjusted using the 16-step internal digital brightness con- trol. The MAX6954 includes a low-power shutdown mode, a scan-limit register that allows the user to display from 1 to 16 digits, segment blinking (synchronized across mul- tiple drivers, if desired), and a test mode, which forces all LEDs on. The LED drivers are slew-rate limited to reduce EMI.

For a 2-wire interfaced version, refer to the MAX6955 data sheet. An evaluation kit (EV kit) for the MAX6955 is available.

Applications

• Set-Top Boxes
• Panel Meters
• White Goods
• Bar Graph Displays
• Audio/Video Equipment

MAX6954: Typical Operating Circuit

• High-Speed 26MHz SPI/QSPI/MICROWIRE^®-Compatible Serial Interface
• 2.7V to 5.5V Operation
• Drives Up to 16 Digits 7-Segment, 8 Digits 14-Segment, 8 Digits 16-Segment, 128 Discrete LEDs, or a Combination of Digit Types
• Drives Common-Cathode Monocolor and Bicolor LED Displays
• Built-In ASCII 104-Character Font for 14-Segment and 16-Segment Digits and Hexadecimal Font for 7-Segment Digits
• Automatic Blinking Control for each Segment
• 10µA (typ) Low-Power Shutdown (Data Retained)
• 16-Step Digit-by-Digit Digital Brightness Control
• Display Blanked on Power-Up
• Slew-Rate Limited Segment Drivers for Lower EMI
• Five GPIO Port Pins Can Be Configured as Key-Switch Reader to Scan and Debounce Up to 32 Switches with n-Key Rollover
• IRQ Output when a Key Input Is Debounced
• 36-Pin SSOP and 40-Pin DIP and TQFN Packages
• Automotive Temperature Range Standard

Links

Max6954 Specification Sheet

Max6954 Main Product Page – Analog Devices