I'd like to use eMMC and NAND memory on custom hardware based on the MX7D. Unlike the SABRE Board, both memorys shall be accessible at the same time.
NAND is multiplexed to SD3+SAI Pins. Theres no alternative. NVCC_SD3 and NVCC_SAI will be powered by a 1.8V PMIC output + Ferrite.
eMMC will use the SD1 pins. SD1 provides 4 data lines (SD1_DATA0..3) and allows to multiplex another 4 (SD1_DATA4..7) on ECSPI2 pins. ECSPI1 and ..2 share the same power domain and SPI1 is in use @ 3V3. The eMMC supports HS200 and HS400 modes at 1.8V only. As a result, I can either use:
- 8 Bit bus width @ 3.3V in normal mode
- 4 Bit bus width @ 1.8V in HS200 mode
I think HS200 on 4 Bit achieves 100 MByte/s data transfer rate while 8 Bit normal mode can reach up to 52 MByte/s?
The eMMC memory provides a Data strobe signal. The i.mx7 does not provide this signal. If I understood correctly it is used in HS400 mode only?
What power rail should be used for the eMMC and NAND pins on the MX7? NAND will be used as the primary boot memory.
The reference design uses the PF3000's NVCC_SD output on SD1 (external SD card), NVCC_3V3 for eMMC, SW2_1V8 for NAND. I wonder if any of the three power rails might be used here (in regard of their specific voltages) or if any specific connections are required to meet startup sequences or any other requirements.