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.
