Hi, Thanks for the response. Quoting "VanBaren, Gerald (AGRE)" <Gerald.VanBaren at smiths-aerospace.com>: > > Well, an uninformed response may be better than no response??? Here > goes... > > I don't understand how your hardware is set up. > > a) Are you connecting the two 64Mbyte chips in parallel as a 32 bit > wide data bus (this is implied by your use of one chip select). This > is contradicted by your statement "My problem is that when i write > some word in first RAM chip is mirrored in the other RAM chip.And > Effectivly
Sorry for the goof up, basically whatever i write to 0th (0x0) memory location in getting replicated to 64th MB (0x4000000) location > i m able to use only 64 MB of RAM." which implies that the two chips > are expected to be sequential in memory address space. > > b) If you are connecting the two chips up sequentially as 64MB by 16 > bits wide on the data bus, you need separate chip selects with the > first one providing the first 64MBytes of decoded address space and > the second one the second 64MBytes. > > Cheap ASCII art: > > a) +----+----++----+----+ 00000000 > |byt0|byt1||byt2|byt3| > | | || | | > | | || | | > +----+----++----+----+ 03FFFFFF > chip0 chip1 The ram chips are connected in above fashion with single chip select. > b) +----+----+ 00000000 > |byt0|byt1| > |byt2|byt3| chip0 > | | | > +----+----+ 01FFFFFF > +----+----+ 02000000 > | | | > | | | chip1 > | | | > +----+----+ 03FFFFFFF > > > -----Original Message----- > > From: Anil Giri [mailto:anil at india.tejasnetworks.com] > > Sent: Monday, November 17, 2003 3:54 AM > > Subject: SDRAM mirroring problem > > > > My board uses SAMSUNG K4S511632M SDRAM in 8M * 16 bit * 4 banks > > configuration (13 rows & 10 columns).Two such chips are used to get > > 128 MB and uses CS1 for chip select.My board uses MPC852T processor. > > > > MPC to SDRAM configuration is as follows: > > ====================== > > A29 :A0 > > A28 :A1 > > A27 :A2 > > A26 :A3 > > A25 :A4 > > A24 :A5 > > A23 :A6 > > A22 :A7 > > A21 :A8 > > A20 :A9 > > GPL_A0 : A10 > > A18 :A11 > > A17 :A12 > > > > A6 :BA0 > > A5 :BA1 > > GPL_A3 :CAS > > GPL_A2 :RAS > > GPL_A5 :WE > > ===================== > > My problem is that when i write some word in first RAM chip is > > mirrored in the other RAM chip.And Effectivly i m able to use only > > 64 MB of RAM. What could be the problem??? Following SDRAM settings > > are used > > > > IMMR:0xff000000 > > OR1: 0xf8000e00 > > BR1: 0x00000081 > > MSTAT:0x00000400 > > MAMR: 0x80a06114 > > MAR: 0x88 > > MCR:0x80002105 ** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
