This version is outdated by a newer approved version.
This version (26 May 2015 19:00) was approved by Lars-Peter Clausen.The Previously approved version (30 Mar 2015 17:42) is available.
This version (26 May 2015 19:00) was approved by Lars-Peter Clausen.The Previously approved version (30 Mar 2015 17:42) is available.This is an old revision of the document!
Table of Contents
SPI Bus Interface
The SPI bus interface carries logical low-level SPI bus signals.
Files
| Name | Description |
|---|---|
| spi_master_rtl.xml | Interface definition file |
Signal Pins
| Name | Direction (Master) | Description |
|---|---|---|
sclk | Output | SPI Clock. |
sdo | Output | SPI SDO (MOSI) signal. |
sdo_t | Output | sdo tri-state enable. If 1 the MOSI signal should be tristated and not be connected to sdo |
sdi | Input | SPI SDI (MISO) signal. |
cs | Output | SPI chip-select signal. |
three_wire | Output | If set to 1 the bus should operate in three-wire mode. In three-wire mode sdi is connected to MOSI instead of MISO. |
IO configuration
The SPI bus interface only carries a logical representation of the low-level SPI bus signals. The top-level module in the FPGA design project is responsible for translating the signal to physical SPI bus signals by instantiating and connecting it to appropriate IO primitives.
The sclk and cs signals can typically be directly connected to a output buffer. sdi should be connected to a mux, that depending on the setting of the three_wire signal connects to a input buffer connected to the miso signal or to a input buffer connected to the mosi signal. The sdo signal should be connected to a output tri-state buffer with the sdo_t signal controlling the tri-state setting.
In some configurations three-wire support may not be required and sdi can directly be connected to the input buffer for the miso signal. Similarly when mosi tri-stating is not required the sdo signal can be directly connected to the mosi signal leaving the sdo_t signal unconnected.
More Information
resources/fpga/peripherals/spi_engine/spi_bus_interface.1432659603.txt.gz · Last modified: 26 May 2015 19:00 by Lars-Peter Clausen