4.8.4.2 MMC1 – Micro SD Interface
The EVM supports a Micro SD card interface connected to MMC1 port of SoC. The Micro SD card socket Mfr.
Part# DM3BT-DSF-PEJS is interfaced with MMC1 port of SoC. This supports UHS1 operation including I/O
operations at both 1.8 V and 3.3 V. The Micro SD card interface is set to operate in SD mode by default.
The I/O voltage is controlled using the LDO that provides the I/O voltage for the MMC1 port. The SD Card
power is provided using a load switch, which is controlled by a GPIO from I/O expander. Control signal
“GPIO_uSD_PWR_EN” is driven by the I2C I/O expander U31 Port02 on the CP board. This I/O expander
is controlled by the processor’s I2C0 port. I2C address of the I/O expander is 0x22.
J7E21E
SOM
VDD_SD from
PMIC
MMC1_SDCD
Micro SD CARD
CONN
DM3BT-DSF-PEJS
VDD_SD
3V3
From GPIO
Expander
EN
Load Switch
TPS22918DB
3V3
VDD_MMC1
22
MMC1_CLK
MMC1_CMD
MMC1_DAT [0:3]
47NŸ
ESD
TPD2E001DRLR
ESD
TPD2E001DRLR
VDD_MMC1
Figure 4-14. micro-SD Card Block Diagram
An ESD protection device Mfr. Part# TPD2E001DRLR is provided for data, clock, command and card detect
signals. The CD (card detect) pin of Micro SD card socket is pulled high and connected to CD pin of SoC. An
external pull up resistor (47K) is provided on data [3:0] and CMD signals to avoid floating.
J721E EVM Hardware Architecture www.ti.com
46 Jacinto7 J721E/DRA829/TDA4VM Evaluation Module (EVM) SPRUIS4D – MAY 2020 – REVISED MARCH 2022
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