When power is first applied to the MAX6954 the device is in shutdown mode, all digits are blanked, the 7-segment font map is selected and the device is set to scan the maximum number of digits. Table 2 contains a list of the initial power-up states of important MAX6954 registers. Segment labeling for 7-aegment displays.Īfter verification of the connections between the MAX6954 and the 7-segment displays the device must be configured for operation with 7-segment displays. Write 0x00 to register 0x07 to exit display test mode.įigure 2. If a segment does not light in display test mode this indicates a connection problem that should be investigated. Enable display test mode by writing 0x01 to register 0x07. Display test mode overrides, but does not alter, all control and digit registers and turns all segments on. Connection Scheme for Sixteen 7-Segment Digits Digitĭisplay test mode can be used to verify connections after connecting the MAX6954 to 7-segment displays. Figure 1 illustrates a sixteen digit, 7-segment application circuit for the MAX6954. The letters in Table 1 correspond to the segment labels shown in Figure 2. Table 1 lists the connection scheme for 7-segment digits that is compatible with the MAX6954 multiplex scheme and the built in hexadecimal font map. The technique is discussed in " Charlieplexing - Reduced Pin-Count LED Display Multiplexing". This differs from the standard LED multiplex connection, which uses separate driver pins for anodes and cathodes. The MAX6954 utilizes a multiplex technique that reduces driver pin count by using ports alternately as cathode and anode drivers. This application note guides the user through the process of connecting the MAX6954 to 7-segment displays and configuring the internal registers to control the displays using the included hexadecimal font map. MAX6954 7-segment application circuit.Ī common application for the MAX6954 is driving up to sixteen 7-segment mono-color LEDs. " Quick-Start: Driving 16-Segment Displays with the MAX6954" and " Quick-Start: Driving 14-Segment Displays with the MAX6954" are similar application notes that discuss configuring the MAX6954 for 16-segment and 14-segment applications, respectively.įigure 1. See the MAX6954 data sheet for additional information about MAX6954 features. This application note shows a typical application and configuration for driving sixteen mono-color, 7-segment LEDs using the MAX6954. The MAX6954 is a versatile display driver, capable of controlling a mix of discrete, 7-segment, 14-segment, and 16-segment LED displays through a serial interface. This article is how-to guide, intended as a quick learning aid for engineers considering using the MAX6954 to drive 7-segment monocolor LEDs.
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