M38260ECFS datasheet(43/91 Pages) RENESAS

43 / 91 page

Rev.1.00

Sep 06, 2006

page 43 of 88

REJ03B0181-0100

3826 Group (One Time PROM version)

CTCSS Function

(Continuous Tone-Controlled Squelch

System)

The CTCSS function is used to generate the sine wave of single

frequency automatically. The CTCSS output waveform can be out-

put from DA2 pin. CTCSS waveform is outputted by setting “1” to

the CTCSS/DA2 output enable bit (bit 1 of address 003616), and

setting “1” to the CTCSS/DA2 selection bit (bit 3 of address

003616). In order to set the frequency of CTCSS output, value is

written in the CTCSS timer. The CTCSS timer consists of a 10-bit

timer. When writing a value to the CTCSS timer, write the low-or-

der byte first.

Rating frequency (Hz)

67.0

77.0

88.5

100.0

107.2

114.8

123.0

131.8

141.3

151.4

162.2

173.8

186.2

203.5

218.1

233.6

250.3

n (Timer value)

465

405

352

312

291

271

253

236

220

205

192

179

167

153

142

133

124

Error frequency (Hz)

0.06

–0.03

0.027

–0.16

–0.18

0.09

0.03

0.06

0.10

0.30

–0.28

–0.19

–0.58

0.43

–0.39

–0.30

Deviation (%)

0.089

–0.038

0.030

–0.160

–0.167

0.078

0.026

0.043

0.073

0.198

–0.174

–0.109

–0.101

–0.284

0.198

–0.167

–0.120

Output frequency (Hz)]

67.06

76.97

88.53

99.84

107.02

114.89

123.03

131.86

141.40

151.70

161.92

173.61

186.01

202.92

218.53

233.20

250.00

Table 10 Example of frequency accuracy (at f(XIN) = 4 MHz)

f (XIN)/2

(n+1) ✕ 64

Vcc

When reading a value from the CTCSS timer, read the high-order

byte first. By the value written in the CTCSS timer is n, the sine

wave of the following frequency is generated.

f =

(Hz)

Set “00616” or more to the CTCSS timer. “0016” is automatically

set to the high-order of the CTCSS timer and “0616” is automati-

cally set to the low-order of the CTCSS timer after reset release.

The amplitude of CTCSS output is obtained by the following for-

mula.

C =

If the D/A2 conversion register is read when the CTCSS function

is selected, the digital value of CTCSS output can be read.

Table 10 shows the example of frequency accuracy (at f(XIN) = 4

MHz).

Fig. 45 Equivalent connection circuit of D/A converter

AVSS

VREF

“0”

“1”

MSB

“0”

“1”

LSB

DAi

DAi conversion register

DAi output enable bit

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