9261的LCD控制口
9261片子的LCDCC引腳我認(rèn)為是用來作為LCD屏的震顫信號用的，但是ATMEL提供的開發(fā)板原理圖上似乎是用來作為液晶屏的LED電壓信號，大家說說自己的看法啊。下面是9261手冊里面的一段說明。
PWM
This block generates the LCD contrast CONTROL signal (LCDCC) to make possible the CONTROL of the DISPLAY's contrast by SOFTWARE. This is an 8-bit PWM (PULSE Width Modulation) signal that can be converted to an ANALOG voltage with a simple passive FILTER.The PWM MODULE has a free-running counter whose VALUE is compared against a compare egister
(CONSTRAST_VAL register). If the VALUE in the counter is less than that in the register, the OUTPUT brings the VALUE of the polarity (POL) bit in the PWM CONTROL register: CONTRAST_CTR.Otherwise, the opposite VALUE is OUTPUT. Thus, a periodic waveform with a PULSE width proportional to the VALUE in the compare register is generated.
Due to the comparison mechanism, the OUTPUT PULSE has a width between zero and 255 PWM counter cycles. Thus by adding a simple passive FILTER outside the chip, an ANALOG voltage between 0 and (255/256) × VDD can be obtained (for the positive polarity case, or between (1/256) × VDD and VDD for the negative polarity case). Other voltage VALUEs can be obtained by adding active external circuitry.For PWM mode, the frequency of the counter can be adjusted to four different VALUEs using field PS of CONTRAST_CTR register.
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