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【工程师经验分享】MicroBlaze访问Zynq-7000的OCM

作者：付汉杰，<a href="mailto:hankf@xilinx.com">hankf@xilinx.com</a&gt;，文章转载自：<a id="link_3" href="https://forums.xilinx.com/t5/%E5%B5%8C%E5%85%A5%E5%BC%8F-%E5%B7%A5%E5%8…;

<strong>1. MicroBlaze AXI访问返回DECODE1C</strong>
在ZC702单板上，MicroBlaze通过IC/DC端口连接到PS S_AXI_GP0，MicroBlaze读取OCM，得到值DECODE1C。
DECODE1C is returned by the AXI Interconnect if it doesn't know how to route a requested AXI transaction.
MicroBlaze改为通过DP端口连接到PS S_AXI_GP0，再读取OCM，正常。

<strong>2. OCM映射到高地址</strong>
Zynq-7000的OCM缺省部分映射到0地址，部分映射到0xFFFF0000。如果要把OCM全部映射到高地址，需要配置OCM_CFG寄存器。MicroBlaze不能访问OCM_CFG寄存器，一定要在A9里访问OCM_CFG寄存器。
<pre>
/*
Register (slcr) OCM_CFG
Absolute Address 0xF8000910
*/
xil_printf("Original OCM_CFG: 0x%08x\r\n", Xil_In32(0xF8000910) );
Xil_Out32(SLCR_UNLOCK, SLCR_UNLOCK_VAL);
Xil_Out32(0xF8000910, 0x1f);
Xil_Out32(SLCR_LOCK, SLCR_LOCK_VAL);
xil_printf("Updated OCM_CFG: 0x%08x\r\n", Xil_In32(0xF8000910) );
</pre>

<strong>3. 参考文章</strong>
https://www.xilinx.com/support/answers/71416.html
https://www.xilinx.com/video/soc/zynq-microblaze-iop-ocm-memory-resourc…