Electronic Components Datasheet Search |
|
HCMS-2974 Datasheet(PDF) 11 Page - Agilent(Hewlett-Packard) |
|
HCMS-2974 Datasheet(HTML) 11 Page - Agilent(Hewlett-Packard) |
11 / 16 page 11 right-most characters. The Dot Registers are connected in series to form a 320-bit dot shift register. The location of pixel 0 has not changed. However, Dot Shift Register bit 0 of IC2 becomes bit 160 of the 320-bit dot shift register. The Control Registers of the two ICs are independent of each other. This means that to adjust the display brightness the same control word must be entered into both ICs, unless the Control Registers are set to simultaneous mode. Longer character string systems can be built by cascading multiple displays together. This is accomplished by creating a five line bus. This bus consists of CE, RS, BL, Reset, and CLK. The display pins are connected to the corresponding bus line. Thus, all CE pins are connected to the CE bus line. Similarly, bus lines for RS, BL, Reset, and CLK are created. Then D IN is connected to the right-most display. D OUT from this display is connected to the next display. The left-most display receives its D IN from the DOUT of the display to its right. D OUT from the left-most display is not used. Each display may be set to use its internal oscillator, or the displays may be synchronized by setting up one display as the master and the others as slaves. The slaves are set to receive their oscillator input from the master’s oscillator output. Sleep mode (Control Word 0, bit D 6 = Low) turns off the Internal Display Oscillator and the LED pixel drivers. This mode is used when the IC needs to be powered up, but does not need to be active. Current draw in sleep mode is nearly zero. Data in the Dot Register and Control Words are retained during sleep mode. Control Word 1 Loading the Control Register with D 7 = logic high selects Control Word 1. This Control Word performs two functions: serial/ simultaneous data out mode and external oscillator prescale select (see Table 2). Serial/Simultaneous Data Output D 0 Bit D 0 of control word 1 is used to switch the mode of D OUT between serial and simultaneous data entry during Control Register writes. The default mode (logic low) is the serial D OUT mode. In serial mode, D OUT is connected to the last bit (D 7) of the Control Shift Register. Storing a logic high to bit D 0 changes D OUT to simultaneous mode which affects the Control Register only. In simultaneous mode, D OUT is logically connected to D IN. This arrangement allows multiple ICs to have their Control Registers written to simul- taneously. For example, for N ICs in the serial mode, N * 8 clock pulses are needed to load the same data in all Control Registers. In the simultaneous mode, N ICs only need 8 clock pulses to load the same data in all Control Registers. The propagation delay from the first IC to the last is N*t DOUTP. External Oscillator Prescaler Bit D 1 Bit D 1 of Control Word 1 is used to scale the frequency of an external Display Oscillator. When this bit is logic low, the external Display Oscillator directly sets the internal display clock rate. When this bit is a logic high, the external oscillator is divided by 8. This scaled frequency then sets the internal display clock rate. It takes 512 cycles of the display clock (or 8 x 512 = 4096 cycles of an external clock with the divide by 8 prescaler) to com- pletely refresh the display once. Using the prescaler bit allows the designer to use a higher external oscillator frequency without extra circuitry. This bit has no affect on the internal Display Oscillator Frequency. Bits D 2-D6 These bits must always be pro- grammed to logic low. Cascaded ICs Figure 3 shows how two ICs are connected within an HCMS-29XX display. The first IC controls the four left-most characters and the second IC controls the four |
Similar Part No. - HCMS-2974 |
|
Similar Description - HCMS-2974 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |