uPD789074 Subseries 8-Bit Single-Chip Microcontrollers UD - Home

CHAPTER 6 16-BIT TIMER 90(2) Buzzer output control register 90 (BZC90)This register selects a buzzer frequency based on fcl selected with the count clock select bits (TCL901 andTCL900), and controls the output of a square wave.BZC90 is set with a 1-bit or 8-bit memory manipulation instruction.RESET input clears BZC90 to 00H.Figure 6-3. Format of Buzzer Output Control Register 90Symbol 7 6 5 4 3 2 1 Address After reset R/WBZC900 0 0 0 BCS902 BCS901 BCS900 BZOE90FF49H 00H R/WBCS902 BCS901 BCS900 Buzzer frequencyfX = 10.0 MHz operation NotefX = 5.0 MHz operation000011110011001101010101fcl = fX/2 2fcl/2 4 156 kHzfcl/2 5 78.1 kHzfcl/2 8 9.77 kHzfcl/2 9 4.88 kHzfcl/2 10 2.44 kHzfcl/2 11 1.22 kHzfcl/2 12 610 Hzfcl/2 13 305 Hzfcl = fX/2 69.77 kHz4.88 kHz610 Hz305 Hz153 Hz76.3 Hz38.1 Hz19.1 Hzfcl = fX/2 439.1 kHz19.5 kHz2.44 kHz1.22 kHz610 Hz305 Hz153 Hz76.3 Hzfcl = fX/2 278.1 kHz39.1 kHz4.88 kHz2.44 kHz1.22 kHz610 Hz305 Hz153 Hzfcl = fX/2 64.88 kHz2.44 kHz305 Hz153 Hz76.3 Hz38.1 Hz19.1 Hz9.54 Hzfcl = fX/2 419.5 kHz9.77 kHz1.22 kHz610 Hz305 Hz153 Hz76.3 Hz38.1 HzBZOE9001Disables buzzer port output.Enables buzzer port output.Buzzer port output controlNote Expanded-specification products only.Caution Bits 4 to 7 must all be set to 0.Remarks 1. fX: System clock oscillation frequency2. fcl: Count clock frequency of 16-bit timer 90.User’s Manual U14801EJ3V1UD 87