at91sam7a3_pmc.html

1、程序目的：介绍AT91SAM7S256-EK TWI的基本用法： 2、 功能说明:通过TWI实现I2C

<tr><td align="CENTER" bgcolor="#FFFFCC">16</td><td align="CENTER"><a name="CKGR_MAINRDY"></a><b>CKGR_MAINRDY</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_MAINRDY">AT91C_CKGR_MAINRDY</a></font></td><td><b>Main Clock Ready</b><br>0 = FMAIN value is not valid or the main oscillator is disabled.<br>1 = The main oscillator has been enabled previously and MAINF value is available.</td></tr>
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<a name="CKGR_PLLR"></a><h4><a href="#PMC">PMC</a>: <i><a href="AT91SAM7A3_h.html#AT91_REG">AT91_REG</a></i> CKGR_PLLR  <i>PLL Register</i></h4><ul><null><font size="-2"><li><b>PMC</b> <i><a href="AT91SAM7A3_h.html#AT91C_PMC_PLLR">AT91C_PMC_PLLR</a></i> 0xFFFFFC2C</font></null></ul><table border=1 cellpadding=0 cellspacing=0 width="100%"><null><th bgcolor="#FFFFCC"><b>Offset</b></th><th bgcolor="#FFFFCC"><b>Name</b></th><th bgcolor="#FFFFCC"><b>Description</b></th><tr><td align="CENTER" bgcolor="#FFFFCC">7..0</td><td align="CENTER"><a name="CKGR_DIV"></a><b>CKGR_DIV</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_DIV">AT91C_CKGR_DIV</a></font></td><td><b>Divider Selected</b><br>2-255 Divider output is the selected clock divided by DIV<font size="-1"><table bgcolor="#E3F2FF" border=1 cellpadding=0 cellspacing=0 width="100%"><null><th><b>Value</b></th><th><b>Label</b></th><th><b>Description</b></th><tr><td align="CENTER">0</td><td align="CENTER"><a name="CKGR_DIV_0"></a><b>CKGR_DIV_0</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_DIV_0">AT91C_CKGR_DIV_0</a></font></td><td><br>Divider output is 0</td></tr>
<tr><td align="CENTER">1</td><td align="CENTER"><a name="CKGR_DIV_BYPASS"></a><b>CKGR_DIV_BYPASS</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_DIV_BYPASS">AT91C_CKGR_DIV_BYPASS</a></font></td><td><br>Divider is bypassed</td></tr>
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<tr><td align="CENTER" bgcolor="#FFFFCC">13..8</td><td align="CENTER"><a name="CKGR_PLLCOUNT"></a><b>CKGR_PLLCOUNT</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_PLLCOUNT">AT91C_CKGR_PLLCOUNT</a></font></td><td><b>PLL Counter</b><br>Specifies the number of slow clock cycles before the LOCK bit is set in PMC_SR after PMC_PLL is written.</td></tr>
<tr><td align="CENTER" bgcolor="#FFFFCC">15..14</td><td align="CENTER"><a name="CKGR_OUT"></a><b>CKGR_OUT</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_OUT">AT91C_CKGR_OUT</a></font></td><td><b>PLL Output Frequency Range</b><font size="-1"><table bgcolor="#E3F2FF" border=1 cellpadding=0 cellspacing=0 width="100%"><null><th><b>Value</b></th><th><b>Label</b></th><th><b>Description</b></th><tr><td align="CENTER">0</td><td align="CENTER"><a name="CKGR_OUT_0"></a><b>CKGR_OUT_0</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_OUT_0">AT91C_CKGR_OUT_0</a></font></td><td><br>Please refer to the PLL datasheet</td></tr>
<tr><td align="CENTER">1</td><td align="CENTER"><a name="CKGR_OUT_1"></a><b>CKGR_OUT_1</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_OUT_1">AT91C_CKGR_OUT_1</a></font></td><td><br>Please refer to the PLL datasheet</td></tr>
<tr><td align="CENTER">2</td><td align="CENTER"><a name="CKGR_OUT_2"></a><b>CKGR_OUT_2</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_OUT_2">AT91C_CKGR_OUT_2</a></font></td><td><br>Please refer to the PLL datasheet</td></tr>
<tr><td align="CENTER">3</td><td align="CENTER"><a name="CKGR_OUT_3"></a><b>CKGR_OUT_3</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_OUT_3">AT91C_CKGR_OUT_3</a></font></td><td><br>Please refer to the PLL datasheet</td></tr>
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<tr><td align="CENTER" bgcolor="#FFFFCC">26..16</td><td align="CENTER"><a name="CKGR_MUL"></a><b>CKGR_MUL</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_MUL">AT91C_CKGR_MUL</a></font></td><td><b>PLL Multiplier</b><br>0 = The PLL is deactivated.<br>1 up to 2047 = The PLL output frequency is the PLL input frequency multiplied by MUL + 1.</td></tr>
<tr><td align="CENTER" bgcolor="#FFFFCC">29..28</td><td align="CENTER"><a name="CKGR_USBDIV"></a><b>CKGR_USBDIV</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_USBDIV">AT91C_CKGR_USBDIV</a></font></td><td><b>Divider for USB Clocks</b><font size="-1"><table bgcolor="#E3F2FF" border=1 cellpadding=0 cellspacing=0 width="100%"><null><th><b>Value</b></th><th><b>Label</b></th><th><b>Description</b></th><tr><td align="CENTER">0</td><td align="CENTER"><a name="CKGR_USBDIV_0"></a><b>CKGR_USBDIV_0</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_USBDIV_0">AT91C_CKGR_USBDIV_0</a></font></td><td><br>Divider output is PLL clock output</td></tr>
<tr><td align="CENTER">1</td><td align="CENTER"><a name="CKGR_USBDIV_1"></a><b>CKGR_USBDIV_1</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_USBDIV_1">AT91C_CKGR_USBDIV_1</a></font></td><td><br>Divider output is PLL clock output divided by 2</td></tr>
<tr><td align="CENTER">2</td><td align="CENTER"><a name="CKGR_USBDIV_2"></a><b>CKGR_USBDIV_2</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_CKGR_USBDIV_2">AT91C_CKGR_USBDIV_2</a></font></td><td><br>Divider output is PLL clock output divided by 4</td></tr>
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<a name="PMC_MCKR"></a><h4><a href="#PMC">PMC</a>: <i><a href="AT91SAM7A3_h.html#AT91_REG">AT91_REG</a></i> PMC_MCKR  <i>Master Clock Register</i></h4><ul><null><font size="-2"><li><b>PMC</b> <i><a href="AT91SAM7A3_h.html#AT91C_PMC_MCKR">AT91C_PMC_MCKR</a></i> 0xFFFFFC30</font></null></ul><table border=1 cellpadding=0 cellspacing=0 width="100%"><null><th bgcolor="#FFFFCC"><b>Offset</b></th><th bgcolor="#FFFFCC"><b>Name</b></th><th bgcolor="#FFFFCC"><b>Description</b></th><tr><td align="CENTER" bgcolor="#FFFFCC">1..0</td><td align="CENTER"><a name="PMC_CSS"></a><b>PMC_CSS</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_CSS">AT91C_PMC_CSS</a></font></td><td><b>Programmable Clock Selection</b><br>Clock selection<font size="-1"><table bgcolor="#E3F2FF" border=1 cellpadding=0 cellspacing=0 width="100%"><null><th><b>Value</b></th><th><b>Label</b></th><th><b>Description</b></th><tr><td align="CENTER">0</td><td align="CENTER"><a name="PMC_CSS_SLOW_CLK"></a><b>PMC_CSS_SLOW_CLK</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_CSS_SLOW_CLK">AT91C_PMC_CSS_SLOW_CLK</a></font></td><td><br>Slow Clock is selected</td></tr>
<tr><td align="CENTER">1</td><td align="CENTER"><a name="PMC_CSS_MAIN_CLK"></a><b>PMC_CSS_MAIN_CLK</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_CSS_MAIN_CLK">AT91C_PMC_CSS_MAIN_CLK</a></font></td><td><br>Main Clock is selected</td></tr>
<tr><td align="CENTER">3</td><td align="CENTER"><a name="PMC_CSS_PLL_CLK"></a><b>PMC_CSS_PLL_CLK</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_CSS_PLL_CLK">AT91C_PMC_CSS_PLL_CLK</a></font></td><td><br>Clock from PLL is selected</td></tr>
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<tr><td align="CENTER" bgcolor="#FFFFCC">4..2</td><td align="CENTER"><a name="PMC_PRES"></a><b>PMC_PRES</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES">AT91C_PMC_PRES</a></font></td><td><b>Programmable Clock Prescaler</b><br>Master clock<font size="-1"><table bgcolor="#E3F2FF" border=1 cellpadding=0 cellspacing=0 width="100%"><null><th><b>Value</b></th><th><b>Label</b></th><th><b>Description</b></th><tr><td align="CENTER">0</td><td align="CENTER"><a name="PMC_PRES_CLK"></a><b>PMC_PRES_CLK</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK">AT91C_PMC_PRES_CLK</a></font></td><td><br>Selected clock</td></tr>
<tr><td align="CENTER">1</td><td align="CENTER"><a name="PMC_PRES_CLK_2"></a><b>PMC_PRES_CLK_2</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK_2">AT91C_PMC_PRES_CLK_2</a></font></td><td><br>Selected clock divided by 2</td></tr>
<tr><td align="CENTER">2</td><td align="CENTER"><a name="PMC_PRES_CLK_4"></a><b>PMC_PRES_CLK_4</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK_4">AT91C_PMC_PRES_CLK_4</a></font></td><td><br>Selected clock divided by 4</td></tr>
<tr><td align="CENTER">3</td><td align="CENTER"><a name="PMC_PRES_CLK_8"></a><b>PMC_PRES_CLK_8</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK_8">AT91C_PMC_PRES_CLK_8</a></font></td><td><br>Selected clock divided by 8</td></tr>
<tr><td align="CENTER">4</td><td align="CENTER"><a name="PMC_PRES_CLK_16"></a><b>PMC_PRES_CLK_16</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK_16">AT91C_PMC_PRES_CLK_16</a></font></td><td><br>Selected clock divided by 16</td></tr>
<tr><td align="CENTER">5</td><td align="CENTER"><a name="PMC_PRES_CLK_32"></a><b>PMC_PRES_CLK_32</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK_32">AT91C_PMC_PRES_CLK_32</a></font></td><td><br>Selected clock divided by 32</td></tr>
<tr><td align="CENTER">6</td><td align="CENTER"><a name="PMC_PRES_CLK_64"></a><b>PMC_PRES_CLK_64</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK_64">AT91C_PMC_PRES_CLK_64</a></font></td><td><br>Selected clock divided by 64</td></tr>
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<a name="PMC_PCKR"></a><h4><a href="#PMC">PMC</a>: <i><a href="AT91SAM7A3_h.html#AT91_REG">AT91_REG</a></i> PMC_PCKR  <i>Programmable Clock Register</i></h4><ul><null><font size="-2"><li><b>PMC</b> <i><a href="AT91SAM7A3_h.html#AT91C_PMC_PCKR">AT91C_PMC_PCKR</a></i> 0xFFFFFC40</font></null></ul><table border=1 cellpadding=0 cellspacing=0 width="100%"><null><th bgcolor="#FFFFCC"><b>Offset</b></th><th bgcolor="#FFFFCC"><b>Name</b></th><th bgcolor="#FFFFCC"><b>Description</b></th><tr><td align="CENTER" bgcolor="#FFFFCC">1..0</td><td align="CENTER"><a name="PMC_CSS"></a><b>PMC_CSS</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_CSS">AT91C_PMC_CSS</a></font></td><td><b>Programmable Clock Selection</b><br>Clock selection<font size="-1"><table bgcolor="#E3F2FF" border=1 cellpadding=0 cellspacing=0 width="100%"><null><th><b>Value</b></th><th><b>Label</b></th><th><b>Description</b></th><tr><td align="CENTER">0</td><td align="CENTER"><a name="PMC_CSS_SLOW_CLK"></a><b>PMC_CSS_SLOW_CLK</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_CSS_SLOW_CLK">AT91C_PMC_CSS_SLOW_CLK</a></font></td><td><br>Slow Clock is selected</td></tr>
<tr><td align="CENTER">1</td><td align="CENTER"><a name="PMC_CSS_MAIN_CLK"></a><b>PMC_CSS_MAIN_CLK</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_CSS_MAIN_CLK">AT91C_PMC_CSS_MAIN_CLK</a></font></td><td><br>Main Clock is selected</td></tr>
<tr><td align="CENTER">3</td><td align="CENTER"><a name="PMC_CSS_PLL_CLK"></a><b>PMC_CSS_PLL_CLK</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_CSS_PLL_CLK">AT91C_PMC_CSS_PLL_CLK</a></font></td><td><br>Clock from PLL is selected</td></tr>
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<tr><td align="CENTER" bgcolor="#FFFFCC">4..2</td><td align="CENTER"><a name="PMC_PRES"></a><b>PMC_PRES</b><font size="-2"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES">AT91C_PMC_PRES</a></font></td><td><b>Programmable Clock Prescaler</b><br>Master clock<font size="-1"><table bgcolor="#E3F2FF" border=1 cellpadding=0 cellspacing=0 width="100%"><null><th><b>Value</b></th><th><b>Label</b></th><th><b>Description</b></th><tr><td align="CENTER">0</td><td align="CENTER"><a name="PMC_PRES_CLK"></a><b>PMC_PRES_CLK</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK">AT91C_PMC_PRES_CLK</a></font></td><td><br>Selected clock</td></tr>
<tr><td align="CENTER">1</td><td align="CENTER"><a name="PMC_PRES_CLK_2"></a><b>PMC_PRES_CLK_2</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK_2">AT91C_PMC_PRES_CLK_2</a></font></td><td><br>Selected clock divided by 2</td></tr>
<tr><td align="CENTER">2</td><td align="CENTER"><a name="PMC_PRES_CLK_4"></a><b>PMC_PRES_CLK_4</b><font size="-1"><br><a href="AT91SAM7A3_h.html#AT91C_PMC_PRES_CLK_4">AT91C_PMC_PRES_CLK_4</a></font></td><td><br>Selected clock divided by 4</td></tr>