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PCD3755FT Datasheet(PDF) 11 Page - NXP Semiconductors |
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PCD3755FT Datasheet(HTML) 11 Page - NXP Semiconductors |
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11 / 32 page  1997 Apr 16 11 Philips Semiconductors Product specification 8-bit microcontrollers with DTMF generator, 8 kbytes OTP and 128 bytes EEPROM PCD3755A; PCD3755E; PCD3755F 6.6 Musical scale frequencies Finally, two octaves of musical scale in steps of semitones can be realized, again assuming an oscillator frequency fxtal = 3.58 MHz (Table 9). It is suggested to define the frequency by the HGF register while the LGF contains 00H, disabling Low Group Frequency generation. Table 9 Musical scale frequencies and their implementation Note 1. Standard scale based on A4 @ 440 Hz. NOTE HGF VALUE (HEX) FREQUENCY (Hz) STANDARD(1) GENERATED D#5 F8 622.3 622.5 E5 EA 659.3 659.5 F5 DD 698.5 697.9 F#5 D0 740.0 741.1 G5 C5 784.0 782.1 G#5 B9 830.6 832.3 A5 AF 880.0 879.3 A#5 A5 923.3 931.9 B5 9C 987.8 985.0 C6 93 1046.5 1044.5 C#6 8A 1108.7 1111.7 D6 82 1174.7 1179.0 D#6 7B 1244.5 1245.1 E6 74 1318.5 1318.9 F6 6D 1396.9 1402.1 F#6 67 1480.0 1482.2 G6 61 1568.0 1572.0 G#6 5C 1661.2 1655.7 A6 56 1760.0 1768.5 A#6 51 1864.7 1875.1 B6 4D 1975.5 1970.0 C7 48 2093.0 2103.3 C#7 44 2217.5 2223.3 D7 40 2349.3 2358.1 D#7 3D 2489.0 2470.4 7 EEPROM AND TIMER 2 ORGANIZATION The PCD3755A, PCD3755E and PCD3755F have 128 bytes of Electrically Erasable Programmable Read-Only Memory (EEPROM). Such non-volatile storage provides data retention without the need for battery backup. In telecom applications, the EEPROM is used for storing redial numbers and for short dialling of frequently used numbers. More generally, EEPROM may be used for customizing microcontrollers, such as to include a PIN code or a country code, to define trimming parameters, to select application features from the range stored in ROM. The most significant difference between a RAM and an EEPROM is that a bit in EEPROM, once written to a logic 1, cannot be cleared by a subsequent write operation. Successive write accesses actually perform a logical OR with the previously stored information. Therefore, to clear a bit, the whole byte must be erased and re-written with the particular bit cleared. Thus, an erase-and-write operation is the EEPROM equivalent of a RAM write operation. Whereas read access times to an EEPROM are comparable to RAM access times, write and erase accesses are much slower at 5 ms each. To make these operations more efficient, several provisions are available in the PCD3755A, PCD3755E and PCD3755F. First, the EEPROM array is structured into 32 four-byte pages (see Fig.5) permitting access to 4 bytes in parallel (write page, erase/write page and erase page). It is also possible to erase and write individual bytes. Finally, the EEPROM address register provides auto-incrementing, allowing very efficient read and write accesses to sequential bytes. To simplify the erase and write timing, the derivative 8-bit down-counter (Timer 2) with reload register is provided. In addition to EEPROM timing, Timer 2 can be used for general real-time tasks, such as for measuring signal duration and for defining pulse widths. |
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