Functional Description
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3-31
3
I
2
C Sequential Read
The I
2
C sequential read can be initiated by either an I
2
C random read
(described here) or an I
2
C current address read.
The first step in the programming sequence of an I
2
C random read
initiation is to test the i2_cmplt bit for the operation-complete status. The
next step is to initiate a start sequence by first setting the i2_start and
i2_enbl bits in the I
2
C Control Register and then writing the device address
(bits 7-1) and write bit (bit 0=0) to the I
2
C Transmitter Data Register. The
i2_cmplt bit is automatically cleared with the write cycle to the I
2
C
Transmitter Data Register.
The I
2
C Status Register must now be polled to test the i2_cmplt and
i2_ackin bits. The i2_cmplt bit becomes set when the device address and
write bit are transmitted, and the i2_ackin bit provides status as to whether
or not a slave device acknowledged the device address. With the successful
transmission of the device address, the initial word address is loaded into
the I
2
C Transmitter Data Register to be transmitted to the slave device.
Again, i2_cmplt and i2_ackin bits must be tested for proper response.
At this point, the slave device is still in a write mode. Therefore, another
start sequence must be sent to the slave to change the mode to read by first
setting the i2_start, i2_ackout, and i2_enbl bits in the I
2
C Control Register
and then writing the device address (bits 7-1) and read bit (bit 0=1) to the
I
2
C Transmitter Data Register. After i2_cmplt and i2_ackin bits are tested
for proper response, the I
2
C master controller writes a dummy value
(data=don’t care) to the I
2
C Transmitter Data Register.This causes the I
2
C
master controller to initiate a read transmission from the slave device.
After the I
2
C master controller has received a byte of data (indicated by
i2_datin=1 in the I
2
C Status Register) and the i2_cmplt bit has also been
tested for proper status, the I
2
C master controller responds with an
acknowledge and the system software may then read the data by polling
the I
2
C Receiver Data Register.
Summary of Contents for MVME5100 Series
Page 1: ...MVME5100 Single Board Computer Programmer s Reference Guide V5100A PG2 September 2001 Edition ...
Page 16: ...xvi ...
Page 20: ...xx ...
Page 28: ...xxviii ...
Page 62: ...1 34 Computer Group Literature Center Web Site Product Data and Memory Maps 1 ...
Page 278: ...3 88 Computer Group Literature Center Web Site System Memory Controller SMC 3 ...
Page 288: ...4 10 Computer Group Literature Center Web Site Hawk Programming Details 4 ...
Page 320: ...Index IN 12 Computer Group Literature Center Web Site I N D E X ...