Entity: I2cSlave
- File: I2cSlave.vhd
Diagram
Description
This file is a part of the GRLIB VHDL IP LIBRARY Copyright (C) 2003 - 2008, Gaisler Research Copyright (C) 2008 - 2012, Aeroflex Gaisler
This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
Entity: i2cslv File: i2cslv.vhd Author: Jan Andersson - Gaisler Research jan@gaisler.com
Documentation of generics:
[TENBIT_G] Support for ten bit addresses.
[I2C_ADDR_G] The slave's i2c address.
[OUTPUT_EN_POLARITY_G] Output enable polarity
[FILTER_G] Length of filters used on SCL and SDA. This generic should specify, in number of system clock cycles plus one, the time of the shortest pulse on the I2C bus to be registered as a valid value. For instance, to disregard any pulse that is 50 ns or shorter in a system with a system frequency of 54 MHz this generic should be set to: ((pulse time) / (clock period)) + 1 = (50 ns) / ((1/(54 MHz)) + 1 = 3.7 The value from this calculation should always be rounded up. In other words an appropriate filter length for a 54 MHz system is 4.
The slave has four different modes operation. The mode is defined by the value of the bits RMODE and TMODE. RMODE TMODE I2CSLAVE Mode 0 0 0 0 1 1 1 0 2 1 1 3
RMODE_G 0: The slave accepts one byte and NAKs all other transfers until software has acknowledged the received byte. RMODE_G 1: The slave accepts one byte and keeps SCL low until software has acknowledged the received byte TMODE_G 0: The slave transmits the same byte to all if the master requests more than one byte in the transfer. The slave then NAKs all read requests unless the Transmit Always Valid (TAV) bit in the control register is set. TMODE_G 1: The slave transmits one byte and then keeps SCL low until software has
acknowledged that the byte has been transmitted.
Modified by Benjamin Reese bareese@slac.stanford.edu Removed APB interface and replaced with generic IO.
Generics
| Generic name | Type | Value | Description |
|---|---|---|---|
| TPD_G | time | 1 ns | |
| TENBIT_G | integer range 0 to 1 | 0 | I2C configuration |
| I2C_ADDR_G | integer range 0 to 1023 | 0 | |
| OUTPUT_EN_POLARITY_G | integer range 0 to 1 | 0 | |
| FILTER_G | integer range 2 to 512 | 4 | |
| RMODE_G | integer range 0 to 1 | 0 | |
| TMODE_G | integer range 0 to 1 | 0 |
Ports
| Port name | Direction | Type | Description |
|---|---|---|---|
| sRst | in | std_ulogic | Synchronous Reset - active high |
| aRst | in | std_ulogic | Asynchronous Reset - active high |
| clk | in | std_ulogic | |
| i2cSlaveIn | in | I2cSlaveInType | Front End |
| i2cSlaveOut | out | I2cSlaveOutType | |
| i2ci | in | i2c_in_type | I2C signals |
| i2co | out | i2c_out_type |
Signals
| Name | Type | Description |
|---|---|---|
| r | i2cslv_reg_type | --------------------------------------------------------------------------- Signals --------------------------------------------------------------------------- Register interface |
| rin | i2cslv_reg_type |
Constants
| Name | Type | Value | Description |
|---|---|---|---|
| I2C_ADDR_LEN_C | integer | 7 + TENBIT_G*3 | |
| I2C_SLAVE_ADDR_C | std_logic_vector((I2C_ADDR_LEN_C-1) downto 0) | conv_std_logic_vector(I2C_ADDR_G, I2C_ADDR_LEN_C) |
|
| I2C_READ_C | std_ulogic | '1' | R/Wn bit |
| I2C_WRITE_C | std_ulogic | '0' | |
| OEPOL_LEVEL_C | std_ulogic | conv_std_logic(OUTPUT_EN_POLARITY_G = 1) | |
| I2C_LOW_C | std_ulogic | OEPOL_LEVEL_C | OE |
| I2C_HIZ_C | std_ulogic | not OEPOL_LEVEL_C | |
| I2C_ACK_C | std_ulogic | '0' | |
| TENBIT_ADDR_START_C | std_logic_vector(4 downto 0) | "11110" | |
| REG_INIT_C | i2cslv_reg_type | ( slvstate => idle, active => false, addr => false, sreg => (others => '0'), cnt => (others => '0'), scl => '0', sda => '0', i2ci => (others => (scl => '0', sda => '0')), scloen => I2C_HIZ_C, sdaoen => I2C_HIZ_C, o => I2C_SLAVE_OUT_INIT_C) |
Types
| Name | Type | Description |
|---|---|---|
| i2c_in_array | --------------------------------------------------------------------------- Types --------------------------------------------------------------------------- | |
| slv_state_type | (idle, checkaddr, check10bitaddr, sclhold, movebyte, handshake) |
|
| i2cslv_reg_type |
Functions
- compaddr1stb ( ibyte : std_logic_vector(7 downto 0)) return boolean
Description
Subprograms
purpose: Compares the first byte of a received address with the slave's
address. The tba input determines if the slave is using a ten bit address.
- compaddr2ndb ( ibyte : std_logic_vector(7 downto 0)) return boolean
Description
purpose: Compares the 2nd byte of a ten bit address with the slave address
Processes
- comb: ( r, sRst, i2ci, i2cSlaveIn )
- reg: ( clk, aRst )