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.
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.
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
Under contruction
MMC
Under contruction
I2C
I2C (Inter-Integrated Circuit) is a multi-master serial computer bus. Omap I2C peripheral implements two signals:
- SDA: Data.
- SCL: Clock.
There are four I2C in Omap, but only three avaliable (I2C4 is used to comunicate with TPS65950).
Under construction
