一. DDR实验

之前关于 IMX6ULL开发板，有关DDR实验。做了DDR内存芯片的初始化，校验与超频测试。

博文链接如下：

IMX6ULL裸机篇之DDR3初始化_凌雪舞的博客-CSDN博客

IMX6ULL裸机篇之DDR3校验与超频测试_凌雪舞的博客-CSDN博客

经过了初始化，校验，超频测试后，最终会存在一个 .inc 后缀的文件，该文件为DDR的初始化配置脚本文件。

DDR实验中，就是 "DDR_256MB.inc" 文件，文件中都是一些关于时钟或DDR寄存器的配置。

"DDR_256MB.inc" 文件中内容即与 DCD数据相一致。

DCD数据：

复位以后， I.MX6U 片内的所有寄存器都会复位为默认值，但是这些默认值往往不是我们

想要的值，而且有些外设我们必须在使用之前初始化它。

为此 I.MX6U 提出了一个 DCD(Device Config Data) 的概念，和 IVT 、 Boot Data 一样， DCD 也是添加到 load.imx 里面的，紧跟在 IVT 和 Boot Data 后面， IVT 里面也指定了 DCD 的位置。 DCD 其实就是 I.MX6U 寄存器地址和对应的配置信息集合， Boot ROM 会使用这些寄存器地址和配置集合来初始化相应的寄存器，比如开启某些外设的时钟、初始化 DDR 等等。

DCD数据结构为："寄存器地址+对应值" 的结构方式，如下所示（参考IMX6ULL驱动开发文档）：

二. 更新 imxdownload.h中寄存器值

更新 imxdownload.h中寄存器的值作用：

如果不更新校验（与超频测试）后的涉及 DDR 的寄存器的值，那么，每次DDR初始化就是错误的。因为裸机篇中给程序添加头部信息会用到 "imxdownload "工具，而头部信息其中就包括 DDR的初始化。

1. imxdownload软件

裸机篇中，正点原子专门编写了一个软件来将编译出来的 .bin 文件烧写到 SD 卡中，这个软件叫做

“ imxdownload ”。

前面裸机篇的实验中，程序不能直接放在 SD卡运行。

imxdownload 所生成的 load.imx 就是在 led.bin 前面加上 IVT+Boot data+DCD这些头数据。

正点原子提供的一个C源码，需要编译生成 imxdownload工具，负责裸机程序的生成。

路径如下所示：

2. 更新 imxdowload.h中DDR寄存器值

这里我用的阿尔法开发板上，DDR芯片型号是 NT5CC128M16JR-EKI，是 256MB 大小的DDR内存芯片，即与正点原子视频中不同（正点原子视频中用的是 512MB）。

左大神讲到，如果用的DDR内存芯片是 128MB 或 2567MB的，经过校准测试完成之后，一定要更新正点原子提供的 download.h中的寄存器的值。

更新方法：更新到与 "DDR_256MB.inc" 配置文件中寄存器的值一致。

DDR_256MB.inc文件内容如下：

//=============================================================================			
//init script for i.MX6UL DDR3			
//=============================================================================			
// Revision History			
// v01			
//=============================================================================			
			
wait = on			
//=============================================================================			
// Disable	WDOG		
//=============================================================================			
setmem /16	0x020bc000 =	0x30	
			
//=============================================================================			
// Enable all clocks (they are disabled by ROM code)			
//=============================================================================			
setmem /32	0x020c4068 =	0xffffffff	
setmem /32	0x020c406c =	0xffffffff	
setmem /32	0x020c4070 =	0xffffffff	
setmem /32	0x020c4074 =	0xffffffff	
setmem /32	0x020c4078 =	0xffffffff	
setmem /32	0x020c407c =	0xffffffff	
setmem /32	0x020c4080 =	0xffffffff	
			
			
//=============================================================================			
// IOMUX			
//=============================================================================			
//DDR IO TYPE:			
setmem /32	0x020e04b4 =	0x000C0000	// IOMUXC_SW_PAD_CTL_GRP_DDR_TYPE 
setmem /32	0x020e04ac =	0x00000000	// IOMUXC_SW_PAD_CTL_GRP_DDRPKE 
			
//CLOCK:			
setmem /32	0x020e027c =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_SDCLK_0
			
//ADDRESS:			
setmem /32	0x020e0250 =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_CAS
setmem /32	0x020e024c =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_RAS
setmem /32	0x020e0490 =	0x00000028	// IOMUXC_SW_PAD_CTL_GRP_ADDDS 
			
//Control:			
setmem /32	0x020e0288 =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_RESET
setmem /32	0x020e0270 =	0x00000000	// IOMUXC_SW_PAD_CTL_PAD_DRAM_SDBA2 - DSE can be configured using Group Control Register: IOMUXC_SW_PAD_CTL_GRP_CTLDS
setmem /32	0x020e0260 =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_SDODT0
setmem /32	0x020e0264 =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_SDODT1
setmem /32	0x020e04a0 =	0x00000028	// IOMUXC_SW_PAD_CTL_GRP_CTLDS 
			
//Data Strobes:			
setmem /32	0x020e0494 =	0x00020000	// IOMUXC_SW_PAD_CTL_GRP_DDRMODE_CTL 
setmem /32	0x020e0280 =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_SDQS0 
setmem /32	0x020e0284 =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_SDQS1 
			
//Data:			
setmem /32	0x020e04b0 =	0x00020000	// IOMUXC_SW_PAD_CTL_GRP_DDRMODE
setmem /32	0x020e0498 =	0x00000028	// IOMUXC_SW_PAD_CTL_GRP_B0DS 
setmem /32	0x020e04a4 =	0x00000028	// IOMUXC_SW_PAD_CTL_GRP_B1DS 
			
setmem /32	0x020e0244 =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_DQM0
setmem /32	0x020e0248 =	0x00000028	// IOMUXC_SW_PAD_CTL_PAD_DRAM_DQM1
			
			
//=============================================================================			
// DDR Controller Registers			
//=============================================================================			
// Manufacturer:	Micron		
// Device Part Number:	MT41K256M16HA-125		
// Clock Freq.: 	400MHz		
// Density per CS in Gb: 	2		
// Chip Selects used:	1		
// Number of Banks:	8		
// Row address:    	14		
// Column address: 	10		
// Data bus width	16		
//=============================================================================			
setmem /32	0x021b001c =	0x00008000	// MMDC0_MDSCR, set the Configuration request bit during MMDC set up
			
//=============================================================================			
// Calibration setup.			
//=============================================================================			
setmem /32	0x021b0800 =	0xA1390003	// DDR_PHY_P0_MPZQHWCTRL, enable both one-time & periodic HW ZQ calibration.
			
// For target board, may need to run write leveling calibration to fine tune these settings.			
setmem /32	0x021b080c  =	0x00000000	
			
//Read DQS Gating calibration			
setmem /32	0x021b083c =	0x013C0138	// MPDGCTRL0 PHY0
			
//Read calibration			
setmem /32	0x021b0848 =	0x40403036	// MPRDDLCTL PHY0
			
//Write calibration                     			
setmem /32	0x021b0850 =	0x4040382C	// MPWRDLCTL PHY0
			
//read data bit delay: (3 is the reccommended default value, although out of reset value is 0)			
setmem /32	0x021b081c =	0x33333333	// MMDC_MPRDDQBY0DL
setmem /32	0x021b0820 =	0x33333333	// MMDC_MPRDDQBY1DL
			
//write data bit delay: 			
setmem /32	0x021b082c =	0xF3333333	// MMDC_MPWRDQBY0DL
setmem /32	0x021b0830 =	0xF3333333	// MMDC_MPWRDQBY1DL
			
//DQS&CLK Duty Cycle			
setmem /32	0x021b08c0 =	0x00921012	// [MMDC_MPDCCR] MMDC Duty Cycle Control Register
			
// Complete calibration by forced measurement:                  			
setmem /32	0x021b08b8 = 	0x00000800	// DDR_PHY_P0_MPMUR0, frc_msr
//=============================================================================			
// Calibration setup end			
//=============================================================================			
			
//MMDC init: 			
setmem /32	0x021b0004 =	0x0002002D	// MMDC0_MDPDC
setmem /32	0x021b0008 =	0x1B333030	// MMDC0_MDOTC
setmem /32	0x021b000c =	0x3F4352F3	// MMDC0_MDCFG0
setmem /32	0x021b0010 =	0xB66D0B63	// MMDC0_MDCFG1
setmem /32	0x021b0014 =	0x01FF00DB	// MMDC0_MDCFG2
			
//MDMISC: RALAT kept to the high level of 5. 			
//MDMISC: consider reducing RALAT if your 528MHz board design allow that. Lower RALAT benefits: 			
//a. better operation at low frequency, for LPDDR2 freq < 100MHz, change RALAT to 3			
//b. Small performence improvment 			
setmem /32	0x021b0018 =	0x00211740	// MMDC0_MDMISC
setmem /32	0x021b001c =	0x00008000	// MMDC0_MDSCR, set the Configuration request bit during MMDC set up
setmem /32	0x021b002c =	0x000026D2	// MMDC0_MDRWD
setmem /32	0x021b0030 =	0x00431023	// MMDC0_MDOR
setmem /32	0x021b0040 =	0x00000047	// Chan0 CS0_END 
setmem /32	0x021b0000 =	0x83180000	// MMDC0_MDCTL
			
setmem /32	0x021b0890 =	0x00400a38	// MPPDCMPR2
			
//Mode register writes                 			
setmem /32	0x021b001c =	0x02008032	// MMDC0_MDSCR, MR2 write, CS0
setmem /32	0x021b001c =	0x00008033	// MMDC0_MDSCR, MR3 write, CS0
setmem /32	0x021b001c =	0x00048031	// MMDC0_MDSCR, MR1 write, CS0
setmem /32	0x021b001c =	0x15208030	// MMDC0_MDSCR, MR0write, CS0
setmem /32	0x021b001c =	0x04008040	// MMDC0_MDSCR, ZQ calibration command sent to device on CS0
			
//setmem /32	0x021b001c =	0x0200803A	// MMDC0_MDSCR, MR2 write, CS1
//setmem /32	0x021b001c =	0x0000803B	// MMDC0_MDSCR, MR3 write, CS1
//setmem /32	0x021b001c =	0x00048039	// MMDC0_MDSCR, MR1 write, CS1
//setmem /32	0x021b001c =	0x15208038	// MMDC0_MDSCR, MR0write, CS1
//setmem /32	0x021b001c =	0x04008048	// MMDC0_MDSCR, ZQ calibration command sent to device on CS1
			
setmem /32	0x021b0020 =	0x00007800	// MMDC0_MDREF
			
setmem /32	0x021b0818 =	0x00000227	// DDR_PHY_P0_MPODTCTRL
			
setmem /32	0x021b0004 =	0x0002556D	// MMDC0_MDPDC now SDCTL power down enabled
			
setmem /32	0x021b0404 =	0x00011006	// MMDC0_MAPSR ADOPT power down enabled, MMDC will enter automatically to self-refresh while the number of idle cycle reached.
			
setmem /32	0x021b001c =	0x00000000	// MMDC0_MDSCR, clear this register (especially the configuration bit as initialization is complete)

imxdownload.h 中代码中，有两个数组，分别为 512MB与 256MB大小的。

数组内部的数据结构分布：寄存器地址+对应值

我这里使用的开发板上的 DDR内存芯片是 256MB。所以，这里是更新 256MB大小的数组内部寄存器的值。根据 "DDR_256MB.inc" 配置文件，更新 imxdownload.h文件中寄存器的值。

imxdownload.h文件中涉及 256MB的数组如下（这里涉及的寄存器的值已经做过更新）：

const int imx6_256mb_ivtdcd_table[256] = {
0X402000D1,0X87800000,0X00000000,0X877FF42C,0X877FF420,0X877FF400,0X00000000,0X00000000,
0X877FF000,0X00076000,0X00000000,0X40E801D2,0X04E401CC,0X68400C02,0XFFFFFFFF,0X6C400C02,
0XFFFFFFFF,0X70400C02,0XFFFFFFFF,0X74400C02,0XFFFFFFFF,0X78400C02,0XFFFFFFFF,0X7C400C02,
0XFFFFFFFF,0X80400C02,0XFFFFFFFF,0XB4040E02,0X00000C00,0XAC040E02,0X00000000,0X7C020E02,
0X28000000,0X50020E02,0X28000000,0X4C020E02,0X28000000,0X90040E02,0X28000000,0X88020E02,
0X28000C00,0X70020E02,0X00000000,0X60020E02,0X28000000,0X64020E02,0X28000000,0XA0040E02,
0X28000000,0X94040E02,0X00000200,0X80020E02,0X28000000,0X84020E02,0X28000000,0XB0040E02,
0X00000200,0X98040E02,0X30000000,0XA4040E02,0X30000000,0X44020E02,0X28000000,0X48020E02,
0X28000000,0X1C001B02,0X00800000,0X00081B02,0X030039A1,0X0C081B02,0X00000000,0X3C081B02,
0X38013C01,0X48081B02,0X36304040,0X50081B02,0X2C384040,0X1C081B02,0X33333333,0X20081B02,
0X33333333,0X2C081B02,0X333333F3,0X30081B02,0X333333F3,0XC0081B02,0X12109200,0XB8081B02,
0X00080000,0X04001B02,0X2D000200,0X08001B02,0X3030331B,0X0C001B02,0XF352433F,0X10001B02,
0X630B6DB6,0X14001B02,0XDB00FF01,0X18001B02,0X40172100,0X1C001B02,0X00800000,0X2C001B02,
0XD2260000,0X30001B02,0X23104300,0X40001B02,0X47000000,0X00001B02,0X00001883,0X90081B02,
0X380A4000,0X1C001B02,0X32800002,0X1C001B02,0X33800000,0X1C001B02,0X31800400,0X1C001B02,
0X30802015,0X1C001B02,0X40800004,0X20001B02,0X00780000,0X18081B02,0X27020000,0X04001B02,
0X6D550200,0X04041B02,0X06100100,0X1C001B02,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,0X00000000,
};

注意：

更新完成 imxdownload.h 文件中的寄存器值后，即以上的数组中的寄存器值后，需要重新编译 imxdownload 工程。最终生成 imxdownload工具。

在后续裸机篇开发中，使用这里新生成的 imxdownload 工具生成 load.imx程序（即添加了头部信息的程序）。

使用经过校验并超频测试后的 DDR寄存器值，运行的程序中 DDR初始化工作才是正确的！！！