
***
Genesis Microchip Confidential ***
gm2115/25 Preliminary Data Sheet
June 2002
44
C2115-DAT-01B
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A serial host interface is provided to allow an external device to peek and poke registers in
the gm2115/25. This is done using a 2-wire serial protocol. Note that 2-wire host interface
requires bootstrap settings as described in Table 16.
The 2-wire host interface is suitable for connection to a factory interrogation port. This is
illustrated in Figure 28. The factory test station connects to the gm2115/25 through the Direct
Data Channel (DDC) of the DSUB15. For example, the PC can make gm2115/25 display test
patterns (see section 4.4). A camera can be used to automate the calibration of the LCD
panel.
DDC
Device-Under-Test
Factory Test Station
Camera
Figure 28.
Factory Calibration and Test Environment
An arbitration mechanism ensures that register accesses from the OCM and the 2-wire host
interface port are always serviced (time division multiplexing).
4.15.1 Host Interface Command Format
Transactions on the 2-wire host protocol occurs in integer multiples of bytes (i.e. 8 bits or
two nibbles respectively). These form an instruction byte, a device register address and/or
one or more data bytes. This is described in Table 17.
The first byte of each transfer indicates the type of operation to be performed by the
gm2115/25. The table below lists the instruction codes and the type of transfer operation. The
content of bytes that follow the instruction byte will vary depending on the instruction
chosen. By utilizing these modes effectively, registers can be quickly configured.
The two LSBs of the instruction code, denoted 'A9' and 'A8' in Table 17 below, are bits 9 and
8 of the internal register address respectively. Thus, they should be set to ‘00’ to select a
starting register address of less than 256, ‘01’ to select an address in the range 256 to 511,
and '10' to select an address in the range 512 to 767. These bits of the address increment in
Address Increment transfers. The unused bits in the instruction byte, denoted by 'x', should be
set to ‘1’.