DSPIC30F6013T-20I/PF【PDF 3/228 页】IC DSPIC MCU/DSP 132K 80TQFP

收藏本站

您好，
买卖IC网欢迎您。
请登录
免费注册

买卖IC网

Sheet目录3879

1页 2页 [3页]4页 5页 6页 7页

dsPIC30F6011/6012/6013/6014

DS70117F-page 98

2006 Microchip Technology Inc.

15.4.2

10-BIT MODE SLAVE RECEPTION

Once addressed, the master can generate a Repeated

Start, reset the high byte of the address and set the

R_W bit without generating a Stop bit, thus initiating a

slave transmit operation.

15.5

Automatic Clock Stretch

In the Slave modes, the module can synchronize buffer

reads and write to the master device by clock stretching.

15.5.1

TRANSMIT CLOCK STRETCHING

Both 10-bit and 7-bit Transmit modes implement clock

stretching by asserting the SCLREL bit after the falling

edge of the ninth clock, if the TBF bit is cleared, indicat-

ing the buffer is empty.

In Slave Transmit modes, clock stretching is always

performed irrespective of the STREN bit.

Clock synchronization takes place following the ninth

clock of the transmit sequence. If the device samples

an ACK on the falling edge of the ninth clock and if the

TBF bit is still clear, then the SCLREL bit is automati-

cally cleared. The SCLREL being cleared to ‘0’ will

assert the SCL line low. The user’s ISR must set the

SCLREL bit before transmission is allowed to continue.

By holding the SCL line low, the user has time to ser-

vice the ISR and load the contents of the I2CTRN

before the master device can initiate another transmit

sequence.

15.5.2

RECEIVE CLOCK STRETCHING

The STREN bit in the I2CCON register can be used to

enable clock stretching in Slave Receive mode. When

the STREN bit is set, the SCL pin will be held low at the

end of each data receive sequence.

15.5.3

CLOCK STRETCHING DURING

7-BIT ADDRESSING (STREN = 1)

When the STREN bit is set in Slave Receive mode, the

SCL line is held low when the buffer register is full. The

method for stretching the SCL output is the same for

both 7 and 10-bit addressing modes.

Clock stretching takes place following the ninth clock of

the receive sequence. On the falling edge of the ninth

clock at the end of the ACK sequence, if the RBF bit is

set, the SCLREL bit is automatically cleared, forcing

the SCL output to be held low. The user’s ISR must set

the SCLREL bit before reception is allowed to continue.

By holding the SCL line low, the user has time to ser-

vice the ISR and read the contents of the I2CRCV

before the master device can initiate another receive

sequence. This will prevent buffer overruns from

occurring.

15.5.4

CLOCK STRETCHING DURING

10-BIT ADDRESSING (STREN = 1)

Clock stretching takes place automatically during the

addressing sequence. Because this module has a

the protocol to wait for the address to be updated.

After the address phase is complete, clock stretching

will occur on each data receive or transmit sequence as

was described earlier.

15.6

Software Controlled Clock

Stretching (STREN = 1)

When the STREN bit is ‘1’, the SCLREL bit may be

cleared by software to allow software to control the

clock stretching. The logic will synchronize writes to the

SCLREL bit with the SCL clock. Clearing the SCLREL

bit will not assert the SCL output until the module

detects a falling edge on the SCL output and SCL is

sampled low. If the SCLREL bit is cleared by the user

while the SCL line has been sampled low, the SCL out-

put will be asserted (held low). The SCL output will

remain low until the SCLREL bit is set, and all other

devices on the I2C bus have de-asserted SCL. This

ensures that a write to the SCLREL bit will not violate

the minimum high time requirement for SCL.

If the STREN bit is ‘0’, a software write to the SCLREL

bit will be disregarded and have no effect on the

SCLREL bit.

15.7

Interrupts

The I2C module generates two interrupt flags, MI2CIF

(I2C Master Interrupt Flag) and SI2CIF (I2C Slave Inter-

rupt Flag). The MI2CIF interrupt flag is activated on

completion of a master message event. The SI2CIF

interrupt flag is activated on detection of a message

directed to the slave.

Note 1: If the user loads the contents of I2CTRN,

setting the TBF bit before the falling edge

of the ninth clock, the SCLREL bit will not

be cleared and clock stretching will not

occur.

2: The SCLREL bit can be set in software,

regardless of the state of the TBF bit.

Note 1: If the user reads the contents of the

I2CRCV, clearing the RBF bit before the

falling edge of the ninth clock, the

SCLREL bit will not be cleared and clock

stretching will not occur.

2: The SCLREL bit can be set in software

regardless of the state of the RBF bit. The

user should be careful to clear the RBF bit

in the ISR before the next receive

sequence in order to prevent an overflow

condition.

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

采购需求

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

我的联系方式