X-Git-Url: https://sigrok.org/gitweb/?p=libsigrokdecode.git;a=blobdiff_plain;f=decoders%2Fi2c%2F__init__.py;h=2a36b060abd5a5a38155072d3f7e420c1ad3eb2c;hp=5216e01602a4498c031532ef71ffa6438b6f3e24;hb=4539e9ca58966ce3c9cad4801b16c315e86ace01;hpb=f9d87f641e55cd643037d81d7221ddc169cdae6b diff --git a/decoders/i2c/__init__.py b/decoders/i2c/__init__.py index 5216e01..2a36b06 100644 --- a/decoders/i2c/__init__.py +++ b/decoders/i2c/__init__.py @@ -1,5 +1,5 @@ ## -## This file is part of the sigrok project. +## This file is part of the libsigrokdecode project. ## ## Copyright (C) 2012 Uwe Hermann ## @@ -14,70 +14,12 @@ ## GNU General Public License for more details. ## ## You should have received a copy of the GNU General Public License -## along with this program; if not, write to the Free Software -## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA +## along with this program; if not, see . ## ''' -I2C protocol decoder. - -The Inter-Integrated Circuit (I2C) bus is a bidirectional, multi-master +I²C (Inter-Integrated Circuit) is a bidirectional, multi-master bus using two signals (SCL = serial clock line, SDA = serial data line). - -There can be many devices on the same bus. Each device can potentially be -master or slave (and that can change during runtime). Both slave and master -can potentially play the transmitter or receiver role (this can also -change at runtime). - -Possible maximum data rates: - - Standard mode: 100 kbit/s - - Fast mode: 400 kbit/s - - Fast-mode Plus: 1 Mbit/s - - High-speed mode: 3.4 Mbit/s - -START condition (S): SDA = falling, SCL = high -Repeated START condition (Sr): same as S -Data bit sampling: SCL = rising -STOP condition (P): SDA = rising, SCL = high - -All data bytes on SDA are exactly 8 bits long (transmitted MSB-first). -Each byte has to be followed by a 9th ACK/NACK bit. If that bit is low, -that indicates an ACK, if it's high that indicates a NACK. - -After the first START condition, a master sends the device address of the -slave it wants to talk to. Slave addresses are 7 bits long (MSB-first). -After those 7 bits, a data direction bit is sent. If the bit is low that -indicates a WRITE operation, if it's high that indicates a READ operation. - -Later an optional 10bit slave addressing scheme was added. - -Documentation: -http://www.nxp.com/acrobat/literature/9398/39340011.pdf (v2.1 spec) -http://www.nxp.com/acrobat/usermanuals/UM10204_3.pdf (v3 spec) -http://en.wikipedia.org/wiki/I2C - -Protocol output format: - -I2C packet: -[, ] - - is one of: - - 'START' (START condition) - - 'START REPEAT' (Repeated START condition) - - 'ADDRESS READ' (Slave address, read) - - 'ADDRESS WRITE' (Slave address, write) - - 'DATA READ' (Data, read) - - 'DATA WRITE' (Data, write) - - 'STOP' (STOP condition) - - 'ACK' (ACK bit) - - 'NACK' (NACK bit) - - is the data or address byte associated with the 'ADDRESS*' and 'DATA*' -command. Slave addresses do not include bit 0 (the READ/WRITE indication bit). -For example, a slave address field could be 0x51 (instead of 0xa2). -For 'START', 'START REPEAT', 'STOP', 'ACK', and 'NACK' is None. - ''' -from .i2c import * - +from .pd import Decoder