WB_SDCARD - Pin Description
The following pin description is for the WB_SDCARD component when used on the schematic. In an OpenBus System, although the same signals are present, the abstract nature of the system hides the pin-level Wishbone interfaces. The external interface signals will be made available as sheet entries, associated with the parent sheet symbol used to reference the underlying OpenBus System.
Table 1. WB_SDCARD pin description.| Name | Type | Polarity/ Bus size | Description |
|---|---|---|---|
| Control Signals | |||
| CLK_I | I | Rise | External (system) clock signal |
| RST_I | I | High | External (system) reset. If this signal is active for at least one full cycle of the external clock signal (CLK_I), all internal registers will be reset. |
| Host Processor Interface Signals | |||
| STB_I | I | High | Strobe signal. When asserted, indicates the start of a valid Wishbone data transfer cycle |
| CYC_I | I | High | Cycle signal. When asserted, indicates the start of a valid Wishbone cycle |
| ACK_O | O | High | Standard Wishbone device acknowledgement signal. When this signal goes high, the Controller (Wishbone Slave) has finished execution of the requested action and the current bus cycle is terminated. |
| ADR_I | I | 3 | Address bus, used to select an internal register of the device for writing to/reading from. |
| DAT_O | O | 32 | Data to be sent to host processor. |
| DAT_I | I | 32 | Data received from host processor. |
| WE_I | I | Level | Write enable signal. Used to indicate whether the current local bus cycle is a Read or Write cycle: 0 = Read |
| SD Card Interface Signals | |||
| SD_DETECT | I | Level | Card Detection State. This signal is used to flag whether or not a card is currently inserted into the SD Card Reader: 0 -- No SD Card inserted The state of this signal line is directly reflected by the detect bit of the Card Detection register (CARD_DET(0)). |
| SD_PROTECT | I | Level | Write Protection State. This signal is used to flag the write status of the SD Card currently inserted into the SD Card Reader: 0 -- The SD Card is Read-only (write protect tab is in the 'locked' position) The state of this signal line is directly reflected by the protect bit of the Card Detection register (CARD_DET(1)). |
| SD_CMD | O | - | Serial Data Out. This data is sent from the host processor to the SD Card. |
| SD_DAT0 | I | - | Serial Data In. This is data received from the SD Card, to be sent to the host processor. |
| SD_CLK | O | - | Serial Clock. This signal is generated by the Controller and is used to clock data in and out during communication with the SD Card. |
| SD_DAT3 | O | Level | Serial Chip Select. Take this signal Low to enable communications with the SD Card. The level of this signal is controlled directly by the cs bit in the Control register (CTRL.1). |