UPD9930 datasheet(47/80 Pages) RENESAS

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µPD9930

4.3.2 Expanded Tone Registers (EXPR1, EXPR2)

(1) Expanded Tone Frequency Registration Procedure

The

µPD9930 can register desired tone frequencies (expanded tone frequencies) in 0.3 to 3.4 kHz range.

Expanded tone register 1 (EXPR1) is for registering expanded tone 1 frequency (high group frequency for DTMF

and single tone). Expanded tone register 2 (EXPR2) is for registering expanded tone 2 frequency (low frequency

for DTMF). The frequency must be specified by 10-bit coefficient (2's complement).

Registration of single tone is done with EXPR1 (single-tone generation is impossible by EXPR2) (refer to Figure

4-10 (a)).

When registering dual tone, set high group in EXPR1 and low group in EXPR2.

Write operation in this register can be executed by continuously writing the expanded tone registration command

and expanded tone data command (refer to Figure 4-10).

Once registered, the frequency is valid until reset or updated.

Figure 4-10 Expanded Tone Frequency Registration Procedure

(a) Expanded tone 1 frequency registration procedure

<1> Set expanded tone 1 registration command in EXPR1.

Expanded tone 1 registration command

EXPR1

100110

EA1

EA0

<2> Set higher-order 8 bits of expanded tone coefficient (expanded tone 1 data command) in EXPR1.

Expanded tone 1 data command

EXPR1

EA9

EA8

EA7

EA6

EA5

EA4

EA3

EA2

Remark EA9 to EA0: Tone 1 frequency 10-bit coefficient

(b) Expanded tone 2 frequency registration procedure

<1> Set expanded tone 2 registration command in EXPR2.

Expanded tone 2 registration command

EXPR2

100111

EB1

EB0

<2> Set higher-order 8 bits of expanded tone coefficient (expanded tone 2 data command) in EXPR2.

Expanded tone 2 data command

EXPR2

EB9

EB8

EB7

EB6

EB5

EB4

EB3

EB2

Remark EB9 to EB0: Tone 2 frequency 10-bit coefficient

Caution After executing the expanded tone registration command, the next command is written as expanded

tone data, so continuously execute the expanded tone data command.

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