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Hi,
There are two dual port RAMs in the OFDM RX. One is SMWO_RxModulation, and another is SMWO_PktBufferBER. The port B on both RAMs are not used. The port A on both RAMs has valide ADDRESS inputs, but the DATA and WE inputs are tied to a constant. It seems to me that both RAMs are not useful. Do I miss something here? If these two RAMs are used, can you tell me what initial values are needed to load to SMWO_RxModulation RAM?
Thanks,
Henry Xu
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These dual-port RAMs are used as part of the shared memory extension for our sysgen2opb design flow (previously discussed here; more details here). The OFDM models are designed specifically for this flow. The dual-port RAMs, RO and RW registers are all processed by sysgen2opb to construct the core's OPB interface, which enables its use in a larger EDK project. Our workshop exercises (labs 2 and 3) walk through the entire sysgen -> sysgen2opb -> XPS design flow. We previously discussed some of the extra steps required to create the OFDM pcore. The initial values for both RAMs are defined in the OFDM Rx init script (BER_RAM_init_values and subcarrier_QAM_Values).
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Thanks. There are 3 modulation schemes. What are the base addresses (demodulation dual-port RAM) for each modulation?
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There are two modulation buffers- one for Tx, another for Rx. Each buffer is interpreted as 4-bits wide and 192 words deep. Each word corresponds to the modulation selection for a subcarrier- 64 for antenna A, 64 for antenna B and 64 for base rate symbols. Each 4-bit value corresponds to the number of information bits which will be loaded in a given subcarrier. We support 0, BPSK, QPSK, 16-QAM and 64-QAM per subcarrier, so each 4-bit value is drawn from [0,1,2,4,6]. The base address of the buffers is specified in the C header file generated by sysgen2opb, included in the ofdm_txrx_mimo driver (ofdm_txrx_mimo.h). For example, the latest driver specifies:
#define ofdm_txrx_mimo_SMWO_RxModulation_OFFSET (OFDM_TXRX_MIMO_OFFSET+0x20000) #define ofdm_txrx_mimo_SMWO_TxModulation_OFFSET (OFDM_TXRX_MIMO_OFFSET+0x30000)
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