Kevin Braun
Quick but comprehensive memory test for the LPC4088's 32MB of SDRAM. The demonstration program executes a single test pass, though it can be easily modified for multiple passes. If a memory error is detected, the test stops immediately and displays failed results. A single pass is performed in less than one second and every memory location contains unique data.
Diff: main.cpp
- Revision:
- 0:947ff5fa24c6
- Child:
- 1:b2b9d3920781
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Tue Dec 31 17:38:48 2013 +0000
@@ -0,0 +1,101 @@
+#include "mbed.h"
+#include "sdram.h"
+
+Serial pc(USBTX, USBRX); //Serial USB communications over mbed USB port
+DigitalOut led1(LED1);
+
+//--------------------------------------------------------------------------------------------------------------------------------------//
+//Test the SDRAM array with pseudo-random data
+//memory size = 0x00800000 (8388608 locations * 4 bytes wide = 33.554432 MB
+
+#define DRAMBASEADDR 0xa0000000
+#define DRAMSIZE 0x00800000
+
+int testSDRAM(uint32_t seed) {
+ volatile uint32_t * const ramBaseAddr = (uint32_t *) DRAMBASEADDR;
+ uint32_t lfsr = seed;
+ uint32_t offsAddr = 0;
+
+ //Fill all memory with pseudo-random data
+ pc.printf(" - Filling all memory, starting with PR seed 0x%08x... ", lfsr);
+ for(offsAddr = 0; offsAddr < DRAMSIZE; offsAddr += 4) {
+ lfsr = (lfsr >> 1) ^ (-(lfsr & 1u) & 0xD0000001u);
+ ramBaseAddr[offsAddr] = lfsr;
+ }
+
+ //force error at highest memory location
+ //ramBaseAddr[0x007ffffc] = 0x12345678;
+
+ //Now compare all that has been written
+ pc.printf("done\r\n - Comparing all memory locations... ");
+ lfsr = seed;
+ for(offsAddr = 0; offsAddr < DRAMSIZE; offsAddr += 4) {
+ lfsr = (lfsr >> 1) ^ (-(lfsr & 1u) & 0xD0000001u);
+ if(ramBaseAddr[offsAddr] != lfsr) {
+ pc.printf("\r\n### Memory compare error!!! addr: %08x sent: %08x recvd: %08x\r\n", offsAddr + DRAMBASEADDR, lfsr, ramBaseAddr[offsAddr]);
+ return -1;
+ }
+ }
+
+ //print first DRAM locations
+ pc.printf("done\r\n");
+
+ //Option to print out first few locations of SDRAM
+ //for(offsAddr = 0; offsAddr < 1024; offsAddr += 16) {
+ // pc.printf("addr: %08x 0: %08x 4: %08x 8: %08x c: %08x\r\n", DRAMBASEADDR + offsAddr, ramBaseAddr[offsAddr],
+ // ramBaseAddr[offsAddr + 4], ramBaseAddr[offsAddr + 8], ramBaseAddr[offsAddr + 12]);
+ //}
+ return 0;
+}
+
+//--------------------------------------------------------------------------------------------------------------------------------------//
+//Initialize the 32MB SDRAM and test it.
+
+#define ONEMBDRAMSIZE (1024*1024)
+
+int alloccount = 0;
+unsigned char *ptr[100] ;
+
+int initSDRAM() {
+ pc.printf("Initializing 32MB SDRAM\r\n");
+ if (sdram_init() == 1) {
+ pc.printf(" - Failed to initialize SDRAM\r\n");
+ return 1;
+ }
+
+ while(1) {
+ ptr[alloccount] = (unsigned char *)malloc(ONEMBDRAMSIZE);
+ //pc.printf (" - Allocated Address = %08x %2d\r\n", ptr[alloccount], alloccount);
+ if(ptr[alloccount] == NULL) {
+ pc.printf(" - Maximum allocatable DRAM memory %dMB\r\n", alloccount);
+ for (int i = 0; i < alloccount; i++) {
+ free(ptr[i]);
+ }
+ alloccount = 0;
+ uint32_t StartSeed = 0xbad1deaf;
+ int testresult = testSDRAM(StartSeed);
+ if(testresult) return(testresult);
+ break;
+ } else {
+ alloccount++ ;
+ }
+ }
+ return 0;
+}
+
+//--------------------------------------------------------------------------------------------------------------------------------------//
+//--------------------------------------------------------------------------------------------------------------------------------------//
+
+int main(void) {
+
+ pc.baud(460800);
+ pc.printf("\r\n\r\nLPC4088 SDRAM memory test\r\n");
+ initSDRAM();
+
+ while(1) {
+ wait_ms(500);
+ led1 = !led1;
+ }
+}
+
+