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ST3917 bảng dữ liệu(PDF) 2 Page - STMicroelectronics |
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ST3917 bảng dữ liệu(HTML) 2 Page - STMicroelectronics |
2 / 16 page PULSE R1 R2 R3 R4 MU/MFI MIC+ 1 2 3 4 5 6 7 8 9 10 28 27 26 25 24 23 22 21 20 19 MIC- GTX C1 C2 C3 MODE/PT OSC SEL HKS RXOUT GND V DD GDTMF 11 12 13 14 18 17 16 15 GRX RXIN I REF V CC LN ILINE LED REG PIN CONNECTIONS PIN DESCRIPTION C1, C2, C3, R4, R3, R2, R1 (Keyboard inputs, Pins 1, 2, 3, 25, 26, 27, 28) The device interfaces with either the standard 2 of 8 with negative common or the single contact (Form A) keyboard. Column 4 of the keypad is connecting to ground. A valid keypad entry is either a single Row con- nected to a single Column or GND simultaneously presented to both a single Row and a single Col- umn. In its quiescent or standby state, during nor- mal off-hook operation, the Rows are initialized at logic level 1 (VDD) and the columns are initialized at logic level 0 (GND). Pulling any row input low enables the on chip oscillator. Keyboard scanning then begins. 123 456 789 * 0# Flas h Tone /P ulse Paus e LND Figure 1 : Keyboard Configuration Scanning consists of Rows and Columns alter- nately switching high through on chip pullups. After both a Row and Column keys have been detected, the debounce counter is enabled and any noise (bouncing contacts, etc) is ignored for a debounce period (TKD) of 32ms. At this time, the keyboard is sampled and if both the Row and Column informa- tion are valid, the information is buffered into the LND location. In the tone mode, if two or more keys in the same row or if two or more keys in the same column are depressed a single tone will be output. The tone will correspond to the common row or common column for which the two keys were pushed. This feature is for test purposes, and single tone will not be redialed. Also in the tone mode, the output tone is continuous in the manual dialing as long as the key is pushed. The output tone duration follows the Table 1. When redialing in the tone mode, each DTMF output is 90ms duration, and the tone sepa- ration (inter signal delay) is 90ms. Table 1 : Output Tone Duration Key Push Time, T Tone Output T < 32ms 32ms < T < 90ms + Tkd T > 90 ms + Tkd No output, ignored by the device 90ms duration Output duration = T - tkd ST3917A - ST3917B 2/16 |
Số phần tương tự - ST3917 |
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Mô tả tương tự - ST3917 |
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