Texas Instruments TMS320C642X manual

TMS320C642x DSP Inter-Integrated Circuit (I2C) Peripheral User's Guide Literature Number: SPRUEN0D March 2011[...]

2 SPRUEN0D – March 2011 Submit Documentation Feedback © 2011, Texas Instruments Incorporated[...]

Preface ....................................................................................................................................... 6 1 Introduction ........................................................................................................................ 7 1.1 Purpose of the Peripheral ....................................[...]

www.ti.com List of Figures 1 I2C Peripheral Block Diagram ............................................................................................. 8 2 Multiple I2C Modules Connected ......................................................................................... 9 3 Clocking Diagram for the I2C Peripheral .............................[...]

www.ti.com List of Tables 1 Operating Modes of the I2C Peripheral ................................................................................ 15 2 Ways to Generate a NACK Bit ........................................................................................... 16 3 Descriptions of the I2C Interrupt Events ................................[...]

Preface SPRUEN0D – March 2011 Read This First About This Manual This document describes the inter-integrated circuit (I2C) peripheral in the TMS320C642x Digital Signal Processor (DSP). The I2C peripheral provides an interface between the DSP and other devices that are compliant with Philips Semiconductors Inter-IC bus (I2C-bus) specification vers[...]

User's Guide SPRUEN0D – March 2011 Inter-Integrated Circuit (I2C) Peripheral 1 Introduction This document describes the operation of the inter-integrated circuit (I2C) peripheral in the TMS320C642x Digital Signal Processor (DSP). The scope of this document assumes that you are familiar with the Philips Semiconductors Inter-IC bus (I2C-bus) s[...]

ICXSR ICDXR ICRSR ICDRR Clock synchronizer Prescaler Noise filters Arbitrator I2C INT ICREVT Peripheral data bus Interrupt to CPU Sync events to EDMA controller SDA SCL Control/status registers CPU EDMA I2C peripheral ICXEVT Introduction www.ti.com 1.3 Functional Block Diagram A block diagram of the I2C peripheral is shown in Figure 1 . Refer to Se[...]

TI device I2C I 2 C EPROM I 2 C I2C TI device V DD Pull-up resistors Serial data (SDA) Serial clock (SCL) controll er www.ti.com Peripheral Architecture 2 Peripheral Architecture The I2C peripheral consists of the following primary blocks: • A serial interface: one data pin (SDA) and one clock pin (SCL) • Data registers to temporarily hold rece[...]

d 7 6 5 PLL1 I2C prescaler Prescaled module clock −−MUST be set to 6.7 to 13.3 MHz I2C input clock External input clock Register bits (ICPSC[IPSC]) I2C clock dividers Register bits (ICCLKL[ICCL]), (ICCLKH[ICCH]) Prescaled module clock frequency = I2C input clock frequency (IPSC + 1) I2C module I2C serial clock on SCL pin T o I2C bus I2C serial [...]

W ait state Start HIGH period SCL from device #1 SCL from device #2 Bus line SCL www.ti.com Peripheral Architecture The prescaler (IPSC bit in ICPSC) must only be initialized while the I2C module is in the reset state (IRS = 0 in ICMDR). The prescaled frequency only takes effect when the IRS bit in ICMDR is changed to 1. Changing the IPSC bit in IC[...]

Data line stable data Change of data allowed SDA SCL SDA SCL ST AR T condition (S) condition (P) STOP Peripheral Architecture www.ti.com 2.4.2 Data Validity The data on SDA must be stable during the high period of the clock (see Figure 5 ). The high or low state of the data line, SDA, can change only when the clock signal on SCL is low. Figure 5. B[...]

SDA SCL MSB Acknowledgement bit from slave (No-)Acknowledgement bit from receiver 1 2 7 8 9 1 2 8 9 Slave address ACK ST AR T condition (S) STOP condition (P) R/W ACK Data S Slave address R/W ACK Data ACK Data ACK P 7 n n 1 1 1 1 1 1 www.ti.com Peripheral Architecture 2.6 Serial Data Formats Figure 7 shows an example of a data transfer on the I2C-b[...]

S 1 1 1 1 1 0 A A 7 A A A A A A A A ACK 0 1 1 8 ACK 1 Data n ACK 1 P 1 A A = 2 MSBs R/W 8 LSBs of slave address Data Data S 1 Data ACK ACK ACK P 1 n n n 1 1 1 1 7 n 7 n 1 1 1 1 1 1 1 1 S Slave address R/W ACK Data ACK S Slave address R/W ACK Data ACK P 1 Any number 1 Any number Peripheral Architecture www.ti.com 2.6.2 10-Bit Addressing Format The 1[...]

www.ti.com Peripheral Architecture 2.7 Endianness Considerations When the device is configured for big-endian mode, in order for the data to be placed in the right side of the register being accessed, access to the I2C registers must be performed as follows: • 8-bit accesses: An offset of 3h must be added to the address of the register being acce[...]

Peripheral Architecture www.ti.com 2.9 NACK Bit Generation When the I2C peripheral is a receiver (master or slave), it can acknowledge or ignore bits sent by the transmitter. To ignore any new bits, the I2C peripheral must send a no-acknowledge (NACK) bit during the acknowledge cycle on the bus. Table 2 summarizes the various ways the I2C periphera[...]

1 0 0 0 1 0 0 0 1 1 1 1 1 0 Device #1 lost arbitration and switches of f Bus line SCL Data from device #1 Data from device #2 Bus line SDA www.ti.com Peripheral Architecture 2.10 Arbitration If two or more master-transmitters simultaneously start a transmission on the same bus, an arbitration procedure is invoked. The arbitration procedure uses the[...]

Peripheral Architecture www.ti.com 2.11 Reset Considerations The I2C peripheral has two reset sources: software reset and hardware reset. 2.11.1 Software Reset Considerations To reset the I2C peripheral, write 0 to the I2C reset (IRS) bit in the I2C mode register (ICMDR). All status bits in the I2C interrupt status register (ICSTR) are forced to th[...]

www.ti.com Peripheral Architecture 2.12.1 Configuring the I2C in Master Receiver Mode and Servicing Receive Data via CPU The following initialization procedure is for the I2C controller configured in Master Receiver mode. The CPU is used to move data from the I2C receive register to CPU memory (memory accessible by the CPU). 1. Enable I2C clock fro[...]

Peripheral Architecture www.ti.com 4. Enable the desired interrupt you need to receive by setting the desired interrupt bit field within ICIMR to enable the particular Interrupt. • AAS = 1; Expect an interrupt when Master's Address matches yours (ICOAR programmed value). • ICRRDY = 1; Expect a receive interrupt when a byte worth data sent [...]

www.ti.com Peripheral Architecture 2.13 Interrupt Support The is capable of interrupting the DSP CPU. The CPU can determine which I2C events caused the interrupt by reading the I2C interrupt vector register (ICIVR). ICIVR contains a binary-coded interrupt vector type to indicate which interrupt has occurred. Reading ICIVR clears the interrupt flag;[...]

Registers www.ti.com 2.16 Emulation Considerations The response of the I2C events to emulation suspend events (such as halts and breakpoints) is controlled by the FREE bit in the I2C mode register (ICMDR). The I2C peripheral either stops exchanging data (FREE = 0) or continues to run (FREE = 1) when an emulation suspend event occurs. How the I2C pe[...]

www.ti.com Registers 3.1 I2C Own Address Register (ICOAR) The I2C own address register (ICOAR) is used to specify its own slave address, which distinguishes it from other slaves connected to the I2C-bus. If the 7-bit addressing mode is selected (XA = 0 in ICMDR), only bits 6-0 are used; bits 9-7 are ignored. The I2C own address register (ICOAR) is [...]

Registers www.ti.com 3.2 I2C Interrupt Mask Register (ICIMR) The I2C interrupt mask register (ICIMR) is used to individually enable or disable I2C interrupt requests. The I2C interrupt mask register (ICIMR) is shown in Figure 14 and described Table 6 . Figure 14. I2C Interrupt Mask Register (ICIMR) 31 8 Reserved R-0 76543210 Reserved AAS SCD ICXRDY[...]

www.ti.com Registers 3.3 I2C Interrupt Status Register (ICSTR) The I2C interrupt status register (ICSTR) is used to determine which interrupt has occurred and to read status information. The I2C interrupt status register (ICSTR) is shown in Figure 15 and described in Table 7 . Figure 15. I2C Interrupt Status Register (ICSTR) 31 16 Reserved R-0 15 1[...]

Registers www.ti.com Table 7. I2C Interrupt Status Register (ICSTR) Field Descriptions (continued) Bit Field Value Description 10 XSMT Transmit shift register empty bit. XSMT indicates that the transmitter has experienced underflow. Underflow occurs when the transmit shift register (ICXSR) is empty but the data transmit register (ICDXR) has not bee[...]

www.ti.com Registers Table 7. I2C Interrupt Status Register (ICSTR) Field Descriptions (continued) Bit Field Value Description 1 NACK No-acknowledgment interrupt flag bit. NACK applies when the I2C is a transmitter (master or slave). NACK indicates whether the I2C has detected an acknowledge bit (ACK) or a no-acknowledge bit (NACK) from the receive[...]

Registers www.ti.com 3.4 I2C Clock Divider Registers (ICCLKL and ICCLKH) When the I2C is a master, the prescaled module clock is divided down for use as the I2C serial clock on the SCL pin. The shape of the I2C serial clock depends on two divide-down values, ICCL and ICCH. For detailed information on how these values are programmed, see Section 2.2[...]

www.ti.com Registers 3.5 I2C Data Count Register (ICCNT) The I2C data count register (ICCNT) is used to indicate how many data words to transfer when the I2C is configured as a master-transmitter-receiver (MST = 1 and TRX = 1/0 in ICMDR) and the repeat mode is off (RM = 0 in ICMDR). In the repeat mode (RM = 1), ICCNT is not used. The value written [...]

Registers www.ti.com 3.6 I2C Data Receive Register (ICDRR) The I2C data receive register (ICDRR) is used to read the receive data. The ICDRR can receive a data value of up to 8 bits; data values with fewer than 8 bits are right-aligned in the D bits and the remaining D bits are undefined. The number of data bits is selected by the bit count bits (B[...]

www.ti.com Registers 3.8 I2C Data Transmit Register (ICDXR) The CPU or EDMA writes transmit data to the I2C data transmit register (ICDXR). The ICDXR can accept a data value of up to 8 bits. When writing a data value with fewer than 8 bits, the written data must be right-aligned in the D bits. The number of data bits is selected by the bit count bi[...]

Registers www.ti.com 3.9 I2C Mode Register (ICMDR) The I2C mode register (ICMDR) contains the control bits of the I2C. The I2C mode register (ICMDR) is shown in shown in Figure 22 and described in Table 14 . Figure 22. I2C Mode Register (ICMDR) 31 16 Reserved R-0 15 14 13 12 11 10 9 8 NACKMOD FREE STT Reserved STP MST TRX XA R/W-0 R/W-0 R/W-0 R-0 R[...]

www.ti.com Registers Table 14. I2C Mode Register (ICMDR) Field Descriptions (continued) Bit Field Value Description 10 MST Master mode bit. MST determines whether the I2C is in the slave mode or the master mode. MST is automatically changed from 1 to 0 when the I2C master generates a STOP condition. See Table 16 . 0 Slave mode. The I2C is a slave a[...]

Registers www.ti.com Table 14. I2C Mode Register (ICMDR) Field Descriptions (continued) Bit Field Value Description 2-0 BC 0-7h Bit count bits. BC defines the number of bits (1 to 8) in the next data word that is to be received or transmitted by the I2C. The number of bits selected with BC must match the data size of the other device. Note that whe[...]

ICDRR ICRSR 0 1 ICSAR ICOAR 0 1 ICDXR ICXSR 0 1 0 0 DLB SCL_IN SCL_OUT Address/data T o internal I2C logic From internal I2C logic T o internal I2C logic T o ARM CPU or EDMA From ARM CPU or EDMA From ARM CPU or EDMA From ARM CPU or EDMA SCL SDA I2C peripheral DLB DLB www.ti.com Registers Table 16. How the MST and FDF Bits Affect the Role of TRX Bit[...]

Registers www.ti.com 3.10 I2C Interrupt Vector Register (ICIVR) The I2C interrupt vector register (ICIVR) is used by the CPU to determine which event generated the I2C interrupt. Reading ICIVR clears the interrupt flag; if other interrupts are pending, a new interrupt is generated. If there are more than one interrupt flag, reading ICIVR clears the[...]

www.ti.com Registers 3.11 I2C Extended Mode Register (ICEMDR) The I2C extended mode register (ICEMDR) is used to indicate which condition generates a transmit data ready interrupt. The I2C extended mode register (ICEMDR) is shown in Figure 25 and described in Table 18 . Figure 25. I2C Extended Mode Register (ICEMDR) 31 16 Reserved R-0 15 1 0 Reserv[...]

Registers www.ti.com 3.12 I2C Prescaler Register (ICPSC) The I2C prescaler register (ICPSC) is used for dividing down the I2C input clock to obtain the desired prescaled module clock for the operation of the I2C. The IPSC bits must be initialized while the I2C is in reset (IRS = 0 in ICMDR). The prescaled frequency takes effect only when the IRS bi[...]

www.ti.com Registers 3.13 I2C Peripheral Identification Register (ICPID1) The I2C peripheral identification registers (ICPID1) contain identification data (class, revision, and type) for the peripheral. The I2C peripheral identification register (ICPID1) is shown in Figure 27 and described in Table 20 . Figure 27. I2C Peripheral Identification Regi[...]

www.ti.com Appendix A Revision History Table 22 lists the changes made since the previous version of this document. Table 22. Document Revision History Reference Additions/Modifications/Deletions Section 1.2 Changed second bullet point. Section 3.5 Changed first sentence in first paragraph. Table 14 Changed Description of RM bit. Table 17 Changed D[...]

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