 |
数据搜索系统，热门电子元器件搜索 |
|
|
数据搜索系统，热门电子元器件搜索 |
|
PIC16F1459-ESOSQTP 数据表(PDF) 73 Page - Microchip Technology |
|
|
|||||||||||||||||||||||||||||
PIC16F1459-ESOSQTP 数据表(HTML) 73 Page - Microchip Technology |
|
|
73 / 418 page  2012 Microchip Technology Inc. Preliminary DS41639A-page 73 PIC16(L)F1454/5/9 5.8 Active Clock Tuning (ACT) The Active Clock Tuning (ACT) continuously adjusts the 16 MHz Internal Oscillator, using an available external reference, to achieve ± 0.20% accuracy. This eliminates the need for a high-speed, high-accuracy external crystal when the system has an available lower speed, lower power, high-accuracy clock source available. Systems implementing a Real-Time Clock Calendar (RTCC) or a full-speed USB application can take full advantage of the ACT. 5.8.1 ACTIVE CLOCK TUNING OPERATION The ACT defaults to the disabled state after any Reset. When the ACT is disabled, the user can write to the TUN<6:0> bits in the OSCTUNE register to manually adjust the 16 MHz Internal Oscillator. The ACT is enabled by setting the ACTEN bit of the ACTCON register. When enabled, the ACT takes control of the OSCTUNE register. The ACT uses the selected ACT reference clock to tune the 16 MHz Internal Oscillator to an accuracy of 16MHz ± 0.2%. The tuning automatically adjusts the OSCTUNE register every reference clock cycle. 5.8.2 ACTIVE CLOCK TUNING SOURCE SELECTION The ACT reference clock is selected with the ACTSRC bit of the ACTCON register. The reference clock sources are provided by the: • USB module in full-speed operation (ACT_clk) • Secondary clock at 32.768 kHz (SOSC_clk) 5.8.3 ACT LOCK STATUS The ACTLOCK bit will be set to '1', when the 16 MHz Internal Oscillator is successfully tuned. The bit will be cleared by the following conditions: • Out of Lock condition • Device Reset • ACT is disabled 5.8.4 ACT OUT-OF-RANGE STATUS If the ACT requires an OSCTUNE value outside the range to achieve ± 0.20% accuracy, then the ACT Out-of-Range (ACTOR) Status bit will be set to '1'. An out-of-range status can occur: • When the 16 MHz internal oscillator is tuned to its lowest frequency and the next ACT_clk event requests a lower frequency. • When the 16 MHz internal oscillator is tuned to its highest frequency and the next ACT_clk event requests a higher frequency. When the ACT out-of-range event occurs, the 16 MHz internal oscillator will continue to use the last written OSCTUNE value. When the OSCTUNE value moves back within the tunable range and ACTLOCK is established, the ACTOR bit is cleared to '0'. FIGURE 5-11: ACTIVE CLOCK TUNING BLOCK DIAGRAM Note 1: When the ACT is enabled, the OSCTUNE register is only updated by the ACT. Writes to the OSCTUNE regis- ter by the user are inhibited, but reading the register is permitted. 2: After disabling the ACT, the user should wait three instructions before writing to the OSCTUNE register. ACTSRC FSUSB_clk SOSC_clk ACTEN Active Clock Tuning ACT_clk Enable ACTEN Write OSCTUNE ACTEN ACTUD 16 MHz Internal OSC 1 0 OSCTUNE<6:0> 7 7 ACT data sfr data |
|
链接网址 |
| ALLDATASHEET是否为您带来帮助? [ DONATE ] |
关于 Alldatasheet | 广告服务 | 联系我们 | 隐私政策 | 数据表链接 | 链接交换 | 制造商名单 All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
Chinese ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
