3.9. SDIO Interfaces¶
Pin |
Signal |
Description |
type |
I/O |
|---|---|---|---|---|
51, 95 |
SD1_CD SD2_CD |
SD Card Detect – connected to a GPIO |
VDDIO |
I |
52, 96 |
SD1_D[0] SD2_D[0] |
SD Data bidirectional signals |
VDDIO |
I/O |
53, 97 |
SD1_D[1] SD2_D[1] |
|||
54, 98 |
SD1_D[2] SD2_D[2] |
|||
55, 99 |
SD1_D[3] SD2_D[3] |
|||
56, 100 |
SD1_CMD SD2_CMD |
SD Command bidirectional signal |
VDDIO |
I/O |
57, 101 |
SD1_CLK SD2_CLK |
SD Output Clock. |
VDDIO |
O |
Module |
Remark |
|||
TX25, TX28, TX48 |
Only one SD-Card available on standard pinout, SD Interface 2 is not used / not connected. |
|||
TX28 |
Pin 101 is used as ENET_CLK. |
|||
The TX pinout provides two dedicated SDIO interfaces. SDIO stands for Secure Digital Input Output which can also be used for SD-Memory-Cards.
3.9.1. SD-Card example diagram using level shifters¶
No external pullups are needed here. Each port of the TXS0108E has an internal pull-up resistor. These have a value of 40 kΩ when the output is driving low and a value of 4 k Ω when the output is driving high. Unfortunately the card detect feature commonly used for Micro-SD cards on DAT3/CD cannot be used. A dedicated card detect switch is required.
3.9.2. SD-Card example diagram only for 3.3V modules¶
Either the use of the processor internal pullups or the use of pullups on the baseboard is possible.
