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PCD3755AP 数据表(PDF) 10 Page - NXP Semiconductors |
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PCD3755AP 数据表(HTML) 10 Page - NXP Semiconductors |
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10 / 32 page ![]() 1997 Apr 16 10 Philips Semiconductors Product specification 8-bit microcontrollers with DTMF generator, 8 kbytes OTP and 128 bytes EEPROM PCD3755A; PCD3755E; PCD3755F 6.4 DTMF frequencies Assuming an oscillator frequency fxtal = 3.58 MHz, the DTMF standard frequencies can be implemented as shown in Table 6. The relationships between telephone keyboard symbols, DTMF frequency pairs and the frequency register contents are given in Table 7. Table 6 DTMF standard frequencies and their implementation; value = LGF, HGF contents Table 7 Dialling symbols, corresponding DTMF frequency pairs and frequency register contents VALUE (HEX) FREQUENCY (Hz) DEVIATION STANDARD GENERATED (%) (Hz) DD 697 697.90 0.13 0.90 C8 770 770.46 0.06 0.46 B5 852 850.45 −0.18 −1.55 A3 941 943.23 0.24 2.23 7F 1209 1206.45 −0.21 −2.55 72 1336 1341.66 0.42 5.66 67 1477 1482.21 0.35 5.21 5D 1633 1638.24 0.32 5.24 TELEPHONE KEYBOARD SYMBOLS DTMF FREQ. PAIRS (Hz) LGF VALUE (HEX) HGF VALUE (HEX) 0 (941, 1336) A3 72 1 (697, 1209) DD 7F 2 (697, 1336) DD 72 3 (697, 1477) DD 67 4 (770, 1209) C8 7F 5 (770, 1336) C8 72 6 (770, 1477) C8 67 7 (852, 1209) B5 7F 8 (852, 1336) B5 72 9 (852, 1477) B5 67 A (697, 1633) DD 5D B (770, 1633) C8 5D C (852, 1633) B5 5D D (941, 1633) A3 5D • (941, 1209) A3 7F # (941, 1477) A3 67 6.5 Modem frequencies Again assuming an oscillator frequency fxtal = 3.58 MHz, the standard modem frequencies can be implemented as in Table 8. It is suggested to define the frequency by the HGF register while the LGF register contains 00H, disabling Low Group Frequency generation. Table 8 Standard modem frequencies and their implementation Notes 1. Standard is V.21. 2. Standard is Bell 103. 3. Standard is Bell 202. 4. Standard is V.23. HGF VALUE (HEX) FREQUENCY (Hz) DEVIATION MODEM GENERATED (%) (Hz) 9D 980(1) 978.82 −0.12 −1.18 82 1180(1) 1179.03 −0.08 −0.97 8F 1070(2) 1073.33 0.31 3.33 79 1270(2) 1265.30 −0.37 −4.70 80 1200(3) 1197.17 −0.24 −2.83 45 2200(3) 2192.01 −0.36 −7.99 76 1300(4) 1296.94 −0.24 −3.06 48 2100(4) 2103.14 0.15 3.14 5C 1650(1) 1655.66 0.34 5.66 52 1850(1) 1852.77 0.15 2.77 4B 2025(2) 2021.20 −0.19 −3.80 44 2225(2) 2223.32 −0.08 −1.68 |
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