Peripherals Summary
From IGEP - ISEE Wiki
Contents
Overview
This article pretends introduce the capabilities of most used peripherals in IGEPv2, with a brief explanation and program examples to make easy to learning it. For more detailed information see this manual.
Feedback and Contributing
At any point, if you see a mistake you can contribute to this How-To.
Peripherals
UART
UART (universal asynchronous receiver/transmitter) convert parallel data from system bus to serial data through a port. At the destination, a second UART re-assembles this data. Each UART contains a shift register which is the fundamental method of conversion between serial and parallel forms. External signals may be of many different forms, IGEPv2 can handle RS232 and RS485 but not all pads have these standards, Omap UART peripheral use CMOS level voltage (1V8). Omap 3530 have three UARTs and Omap 3730 (DM3730) have four UARTs. Omap UART peripheral use four signals:
- UART TX: Transmit signal.
- UART RX: Receive signal.
- UART RTS: Ready to send, used in RS485 and unidirectional communication.
- UART CTS: Clear to send, used in RS485 and unidirectional communication.
The speed transmion data is mesured in bauds per second, for example Kernel console params uses 115200 bps (equivalent to 14 Kbytes per second). The speed can set up from 300 bauds to 3686400 bauds.
More information: http://en.wikipedia.org/wiki/Universal_asynchronous_receiver/transmitter
GPIO
GPIO (General Purpose Input/Output) is a generic pin on a chip whose behavior (including whether it is an input or output pin) can be controlled (programmed) through software. Some Omap GPIO characteristics are:
- Set the data input and output direction
- Configure GPIO pin to high or low states.
- Configure GPIO pins for interrupt control
- Enable and disable interrupts
- Enable and disable wakeup capability per GPIO pin.
Omap use CMOS voltage levels (1V8) and the pads are connected directly to it.
More information go:
- http://en.wikipedia.org/wiki/GPIO
- http://omappedia.org/wiki/GPIO
How to use GPIOs Example: What can I do with IGEP0020#How_to_handle_the_gpio-LED.27s
SPI
SPI (Serial Peripheral Interface Bus) is a synchronous serial data link. Devices communicate in master/slave mode where the master device initiates the data frame. Multiple slave devices are allowed with individual slave select (chip select) lines. It can be fater than I2C protocol and it is uasully used i short distances, it uses CMOS level voltage (1V8). Omap have four SPIs: SPI1 supports up to four peripherals, SPI2 and SPI3 support up to two
peripherals, and SPI4 supports only one peripheral. Omap SPI is named McSPI (Multichannel Serial Peripheral Interface Bus).
Omap McSPI have the next caractheristics:
- Supports DMA for data transfer operations, for reduce CPU usage.
- Supports full duplex data transfer operations, simultaneous comunication between master and slave.
- Supports configuration of number of wordlength.
- Supports configuration of phase and polarity of the device functional clock for each channel.
- Support configuration of the bitrate for each channel. Between 1.5 KHz and 48 MHz
Omap McSPI peripheral use five signals:
- McSPI_CSO: Chip Select 0.
- McSPI_CS1: Chip Select 1.
- McSPI_SOMI: Slave output master input data.
- McSPI_SIMO: Slave input master output data.
- McSPI_CLK: Clock.
More information:
http://omappedia.org/wiki/Kernel_McSPI
http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus
BSP
BSP (Buffered Serial Port) named in Omap McBSP (Multichannel Buffered Serial Port). This port provides a full-duplex direct serial interface between the device and other devices in a system such as other application chips (digital base band), audio and voice codec (power management device), etc. Because of its high level of versatility, it can accommodate to a wide range of peripherals and clocked frame oriented protocols.
Omap have five BSP peripherals (McBSP1, McBSP2, McBSP3, McBSP4 and McBSP5).
List of recommended usage (non exhaustive) per McBSP modules in the device:
- McBSP1: Digital baseband (DBB) Data
- McBSP2: Audio data with audio buffer and SIDETONE feature
- McBSP3: Bluetooth voice data with SIDETONE feature
- McBSP4: DBB voice data
- McBSP5: Midi data
- McBSP_DX: Transmited serial data.
- McBSP_CLKX: Transmit serial clock.
- McBSP_FSX: Transmit frame syncronization
- McBSP_DR: Received serial data.
- McBSP_CLKR: Received serial clock
- McBSP_FSR:Received frame syncronization.
More information:
http://omappedia.org/wiki/Kernel_McBSP
Under contruction
MMC
MMC (Multimedia Controller) is peripheral than can manage SD/MMC/SDIO , but other peripherals can be controled with this interface like Wlan. The MMC/SD/SDIO host controller deals with MMC/SD/SDIO protocol at transmission level, data packing, adding cyclic redundancy checks (CRC), start/end bit, and checking for syntactical correctness. Data transfers between the MMC controller and a memory card can use one bidirectional data line (for the MMC protocol) or four parallel data lines (for the SD protocol). There are three MMC peripherals (MMC1, MMC2 and MMC3).
- MMC_DAT7: SD/MMC data pin 7. Used by SDIO.
- MMC_DAT6: SD/MMC data pin 6. Used by SDIO.
- MMC_DAT5: SD/MMC data pin 5. Used by SDIO.
- MMC_DAT4: SD/MMC data pin 4. Used by SDIO.
- MMC_DAT3: SD/MMC data pin 3. Used in SD card default data mode.
- MMC_DAT2: SD/MMC data pin 2. Used in SD card default data mode.
- MMC_DAT1: SD/MMC data pin 1. Used in SD card default data mode.
- MMC_DAT0: SD/MMC data pin 0. Used in MMC and SD card default data mode.
- MMC_CMD: SD/MMC command signal.
- MMC_CLK0: SD/MMC clock signal.
Some especifications are:
- Full compliance with MMC command/response sets as defined in the Multimedia Card System Specification, v4.2 including high-capacity (size > 2GB) cards HC MMC.
- Full compliance with SD command/response sets as defined in the SD Memory Card Specifications, v2.0 including high-capacity SDHC cards up to 32GB.
- Full compliance with SDIO command/response sets and interrupt/read-wait mode as defined in the SDIO Card Specification, Part E1, v2.00
- Full compliance with sets as defined in the SD Card Specification, Part A2, SD Host Controller Standard Specification, v2.00
- Full compliance with MMC bus testing procedure as defined in the Multimedia Card System Specification, v4.2
- Full compliance with CE-ATA command/response sets as defined in the CE-ATA Standard Specification
- Built-in 1024-byte buffer for read or write
- 32-bit-wide access bus to maximize bus throughput
- Designed for low power
- Programmable clock generation
- Support SDIO Read Wait and Suspend/Resume functions
- Support:
- 1-bit or 4-bit transfer mode specifications for SD and SDIO cards
- 1-bit, 4-bit, or 8-bit transfer mode specifications for MMC cards
I2C
I2C (Inter-Integrated Circuit) is a multi-master serial computer bus.
Omap I2C peripheral implements two signals:
- SDA: Data. Open-drain output buffer. Requires external pullup resistor.
- SCL: Clock, master device generate it. Open-drain output buffer. Requires external pullup resistor.
There are four I2C in Omap, but only three avaliable (I2C4 is used to comunicate with TPS65950). Their caracteristics are:
- Uses CMOS voltage levels (1V8)
- Compliance with Philips I2C specification version 2.1
- Support for standard mode (up to 100K bits/s), fast mode (up to 400K bits/s) and HS mode for transfer up to 3.4M bits/s
- Support for 3-wire/2-wire SCCB master mode for I2C2 and I2C3 modules, 2-wire SCCB master mode for I2C1 module, up to 100K bits/s
- 7-bit and 10-bit device addressing modes
- General call
- Start/restart/stop
- Multimaster transmitter/slave receiver mode
- Multimaster receiver/slave transmitter mode
- Combined master transmit/receive and receive/transmit mode
- Built-in FIFO for buffered read or write:
– 8 bytes for I2C1 and I2C2
– 64 bytes for I2C3
- Module enable/disable capability
- Programmable clock generation
- 8-bit-wide data access
- Low-power consumption design
- Two DMA channels
- Wide interrupt capability
More information:
http://omappedia.org/wiki/Kernel_I2C
http://en.wikipedia.org/wiki/I%C2%B2C
Under construction
