timer & counter
TRANSCRIPT
Timer & Counter
Perbedaan Timer & Counter
• Timer dan Counter sebenarnya idektik, namun perbedaannya yaitu timer mencacah pulsa dari osilator, sedangkan counter mencacah keadaan tertentu.
Timer/Counter AVR AtMega
• 8bit timer/counter0 dengan PWM• 16bit timer/counter 1• 8bit timer counter 2 dengan PWM dan
pengoperasian asinkron
8bit timer/counter0 dengan PWM
• Clock timer counter dapat menggunakan sumber eksternal (T0) maupun internal tergantung pengaturan dari Timer/Counter Control Register (TCCR0).
• Register 8 bitnya terletak pada TCNT0 (Timer/Counter) dan OCR0 (Output Compare Register)
• Timer/counter dalam keadaan tidak aktif saaat tidak ada sumber clock yang dipilih
• Batas kemampuan mencacah dari 0 hingga 255
Block Diagram
Fitur
• Single Compare Unit Counter• Clear Timer on Compare Match (Auto Reload)• Glitch-free, Phase Correct Pulse Width Modulator
(PWM)• Frequency Generator• External Event Counter• 10-bit Clock Prescaler• Overflow and Compare Match Interrupt Sources
(TOV0 and OCF0)
Mode Operasi
• Normal Mode– Paling simple, selalu increement, otomatis restart saat
mencacah maksimum(0xFF), • Clear Timer on Compare Match (CTC) Mode– Manipulasi resolusi counter pada OCR0, counter kembali
ke nol saat nilainya sama dengan OCR0, • Fast PWM Mode– Menawarkan pembangkitan PWM berfrekuensi tinggi
• Phase Correct PWM Mode– Menawarkan pembangkitan PWM beresolusi tinggi
Register
• Bit 7 – FOCO : perbandingan kemampuan output
• Bit 3, 6 WGM01:0: Waveform Generation Mode• Bit 5:4 COM01:0: Compare Match Output Mode• Bit 2:0 CS02:0: Clock Select• Bit 1 OCIE0: Timer/Counter0 Output Compare
Match Interrupt Enable
16bit timer/counter 1
• Menggunaka Prosedur khusus saat mengakses 16 bit register
• Clock timer counter dapat menggunakan sumber eksternal (T1) maupun internal).
• Batas kemampuan mencacah dari 0 hingga 65535
• Memiliki mode tambahan Phase and Frequency Correct PWM mode
Block Diagram
Fitur• True 16-bit Design (that is, allows 16-bit PWM)• Two Independent Output Compare Units• Double Buffered Output Compare Registers• One Input Capture Unit• Input Capture Noise Canceler• Clear Timer on Compare Match (Auto Reload)• Glitch-free, Phase Correct Pulse Width Modulator (PWM)• Variable PWM Period• Frequency Generator• External Event Counter• Four Independent Interrupt Sources (TOV1, OCF1A, OCF1B, and ICF1)
Mode
• Normal Mode• Clear Timer on Compare Match (CTC) Mode• Fast PWM Mode• Phase Correct PWM Mode• Phase and Frequency Correct PWM mode
Register A
• Bit 7:6 COM1A1:0: Compare Output Mode for Channel A
• Bit 5:4 COM1B1:0: Compare Output Mode for Channel B
• Bit 3 FOC1A: Force Output Compare for Channel A
• Bit 2 FOC1B: Force Output Compare for Channel B
• Bit 1:0 WGM11:0: Waveform Generation Mode
Register B
• Bit 7 ICNC1: Input Capture Noise Canceler
• Bit 6 ICES1: Input Capture Edge Select• Bit 5 Reserved Bit• Bit 4:3 WGM13:2: Waveform Generation
Mode• Bit 2:0 CS12:0: Clock Select
8bit timer/counter 2 dengan PWM dan pengoperasian asinkron
• Clock timer counter dapat menggunakan sumber eksternal (T2) maupun internal.
• Ataupun diatur secara asinkron melalui TOSC1/2 pin• Pengoperasian secara asinkron diatur oleh
Asynchronous Status Register (ASSR)• Register 8 bitnya terletak pada TCNT2
(Timer/Counter) dan OCR2 (Output Compare Register)
• Batas kemampuan mencacah dari 0 hingga 255
Block Diagram
Fitur
• Single Compare unit Counter• Clear Timer on Compare Match (Auto Reload)• Glitch-free, Phase Correct Pulse Width Modulator
(PWM)• Frequency Generator• 10-bit Clock Prescaler• Overflow and Compare Match Interrupt Sources (TOV2
and OCF2)• Allows clocking from External 32 kHz Watch Crystal
Independent of the I/O Clock
Operasi Asinkron ASSR
• Bit 3 AS2: Asynchronous Timer/Counter2• Bit 2 TCN2UB: Timer/Counter2 Update
Busy• Bit 1 OCR2UB: Output Compare Register2
Update Busy• Bit 0 TCR2UB: Timer/Counter Control
Register2 Update Busy