external sram interface lpc2292
2004-09-09 by douglasbolton
Is anybody else using the external bus to interface on the lpc2292. I have 16 bit Sram and an 8 bit device connected to the external bus. Everything works fine except after a power on reset. I have to put a delay in software of a few hundred milliseconds after setting up the bus for the sram to work correctly. If after power on I toggle the reset line it always works. All the voltages are stable when the micro comes out of power on reset but it won't access the sram correctly without a software delay. I've tried extending the time the reset line is enabled during power on to make sure all voltages are stable but it does not help. Below is the code I'm using to set up the sram on CS1, I've put in maximum waits but it doesn't help dummy = PINSEL2; // set extended memory D0-D16 CS,CS1,CS2,CS3 A0-A19 dummy &= ~(0x00000020); dummy |= 0x00000010; // enable /WE,/CS1 dummy |= 0x00000900; // enable /CS2,/CS3 dummy |= 0x00014000; // enable A0,A1, A2-A19 dummy |= 0x0d800000; PINSEL2 = dummy; // set up the external sram on CS1 dummy = BCFG1; // maximum idle cycles dummy |= 0x0000000f; // maximum wait cycles, 16 bit wide bus dummy |= 0x000007e0; // maximum wait cycles dummy |= 0x0000f800; // 16 bit bus dummy &= ~(0x30000000); dummy |= 0x10000000; BCFG1 = dummy;