 |
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 |
|
ADE7569 数据表(PDF) 127 Page - Analog Devices |
|
|
|||||||||||||||||||||||||||||
ADE7569 数据表(HTML) 127 Page - Analog Devices |
|
|
127 / 144 page  ADE7566/ADE7569/ADE7166/ADE7169 Rev. A | Page 127 of 144 Rx RI FE EXTEN = 1 D7 D6 D5 D4 D3 D2 D1 D0 STOP START SBAUDF is the fractional divider ratio required to achieve the required baud rate. The appropriate value for SBAUDF can be calculated with the following formula: ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − × × × = + 1 2 16 64 Rate Baud f SBAUDF SBTH DIV CORE Figure 106. UART Timing in Mode 1 Note that SBAUDF should be rounded to the nearest integer. After the values for DIV and SBAUDF are calculated, the actual baud rate can be calculated with the following formula: Rx RI FE EXTEN = 1 D7 D6 D5 D4 D3 D2 D1 D0 D8 STOP START ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ + × × = + 64 1 2 16 SBAUDF f Rate Baud Actual SBTH DIV CORE Figure 107. UART Timing in Mode 2 and Mode 3 For example, to obtain a baud rate of 9600 bps while operating at a core clock frequency of 4.096 MHz with the PLL CD bits equal to 0, The 8052 standard UART does not provide break error detection. However, for an 8-bit UART, a break error can be detected when the received character is 0, a null character, and when there is no stop bit because the RB8 bit is low. Break error detection is not possible for a 9-bit 8052 UART because the stop bit is not recorded. The ADE7566/ADE7569/ADE7166/ADE7169 enhanced break error detection is available through the BE bit in the SBAUDT SFR. () 4 74 . 4 2 log 9600 16 4,096,000 log = = ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ × = + SBTH DIV Note that the DIV result is rounded down. 0x2B 67 . 42 1 9600 2 16 000 , 096 , 4 64 3 = = ⎟ ⎠ ⎞ ⎜ ⎝ ⎛ − × × × = SBAUDF The 8052 standard UART prevents overwrite errors by not allowing a character to be received when the RI, receive interrupt flag, is set. However, it does not indicate if a character has been lost because the RI bit is set when the frame is received. The enhanced UART overwrite error detection provides this infor- mation. When the enhanced 8052 UART is enabled, a frame is received regardless of the state of the RI flag. If RI = 1 when a new byte is received, the byte in SCON is overwritten, and the overwrite error flag is set. The overwrite error flag is cleared when SBUF is read. Thus, the actual baud rate is 9570 bps, resulting in a 0.31% error. UART ADDITIONAL FEATURES Enhanced Error Checking The extended UART provides frame error, break error, and overwrite error detection. Framing errors occur when a stop bit is not present at the end of the frame. A missing stop bit implies that the data in the frame may not have been received properly. Break error detection indicates whether the Rx line has been low for longer than a 9-bit frame. It indicates that the data just received, a 0 or null character, is not valid because the master has disconnected. Overwrite error detection indicates when the received data has not been read fast enough and, as a result, a byte of data has been lost. The extended UART is enabled by setting the EXTEN bit in the Configuration SFR (CFG, 0xAF). UART TxD Signal Modulation There is an internal 38 kHz signal that can be OR’ed with the UART transmit signal for use in remote control applications (see the 38 kHz Modulation section). The 8052 standard UART offers frame-error checking for an 8-bit UART through the SM2 and RB8 bits. Setting the SM2 bit prevents frames without a stop bit from being received. The stop bit is latched into the RB8 bit in the Serial Communications Control Register Bit Description SFR (SCON, 0x98). This bit can be examined to determine if a valid frame was received. The 8052 does not, however, provide frame error checking for a 9-bit UART. This enhanced error checking functionality is available through the frame error bit, FE, in the Enhanced Serial Baud Rate Control SFR (SBAUDT, 0x9E). The FE bit is set on framing errors for both 8-bit and 9-bit UARTs. One of the events that can wake the MCU from sleep mode is activity on the Rx pin (see the 3.3 V Peripherals and Wake-Up Events section). |
|
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
