![](/media/cache/profiles/1f50893f80d6830d62765ffad7721742.50x50_q85.jpg)
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.
main.cpp
- Committer:
- loopsva
- Date:
- 2013-12-31
- Revision:
- 1:b2b9d3920781
- Parent:
- 0:947ff5fa24c6
File content as of revision 1:b2b9d3920781:
#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; break; } else { alloccount++ ; } } return 0; } //--------------------------------------------------------------------------------------------------------------------------------------// //--------------------------------------------------------------------------------------------------------------------------------------// int main(void) { pc.baud(460800); pc.printf("\r\n\r\nLPC4088 SDRAM memory test\r\n"); initSDRAM(); uint32_t StartSeed = 0xbad1deaf; int testresult = testSDRAM(StartSeed); while(1) { wait_ms(500); led1 = !led1; } }