Using the Memory Controller Interface

Memory Controller Interface functionality

• Each of the Convey application engines are connected to 8 MCs (Memory Controllers) through 300MHz DDR interface.
• Each of the 8 MC interfaces consists of two 150MHz ports (odd port and even port). So, the MC interface contains a total of 16 port.
• The data from the two even and odd ports are multiplexed onto the same 300 MHz channel in the MC interface.
• Each of the even and odd ports has its request signals and response signals.
• Refer to section 9.3.3.1 in the PDK for further informations.

Memory Controller Interface Signals

The 4th MC interface of the 8 MC interfaces has the signals shown in the table below. There exist MC interfaces for n = 0 to 7. Also, you can notice that the signals are the same for the even and odd port. However, the signals for the even port use the suffix _e and the signals for the odd port use the suffix _o

Even Port	Odd Port
mc4_req_ld_e	mc4_req_ld_o
mc4_req_st_e	mc4_req_st_o
mc4_req_size_e<1:0>	mc4_req_size_o<1:0>
mc4_req_vadr_e<47:0>	mc4_req_vadr_o<47:0>
mc4_req_wrd_rdctl_e<63:0>	mc4_req_wrd_rdctl_o<63:0>
mc4_req_flush_e	mc4_req_flush_o
mc4_rd_rq_stall_e	mc4_rd_rq_stall_o
mc4_wr_rq_stall_e	mc4_wr_rq_stall_o
mc4_rsp_push_e	mc4_rsp_push_o
mc4_rsp_stall_e	mc4_rsp_stall_o
mc4_rsp_data_e<63:0>	mc4_rsp_data_o<63:0>
mc4_rsp_rdctl_e<31:0>	mc4_rsp_rdctl_o<31:0>
mc4_rsp_flush_cmplt_e	mc4_rsp_flush_cmplt_o

Reading from Memory

• Before requesting any read from the memory, you have to make sure that mci_rd_rq_stall_* = '0', where i is the MC interface port number (could be from 0 to 7).
• To request a read from memory, you have to assert the signal mci_req_ld_* and put the address of the data you want to read on the port mci_req_vadr_*.
• The mci_req_size_*<1:0> is used to indicate if you want to read a byte, word, double-word or quad-word (i.e. 0x0 for byte, and 0x3 for quad-word).
• The lower 31 bits of mci_req_wrd_rdctl_*<63:0> will be returned as mci_req_wrd_rdctl_*<63:0>. You should set it while requesting a read and check it in the response to identify your request.

Writing to Memory

• Before requesting any read from the memory, you have to make sure that mci_wr_rq_stall_* = '0'.
• To request a write to memory, you have to assert the signal mci_req_st_* and put the address of the data you want to write to on the port mci_req_vadr_*.
• The mci_req_size_*<1:0> is used to indicate the size as in the read scenario above.
• The data you want to write should goes on mci_req_wrd_rdctl_*<63:0> bus.