Proprietary and Confidential Information of YAMAR Electronics Ltd.
T
1
HDC
HDI
start
bit
0
1
2
3
0
T
3
Address
stop
start
bit
bit
1
2
3
4
5
6
7
d
a
t
a
Configuration Data
stop
bit
start
bit
Data
T
2
T
3
>1/half bit rate
Figure 4.3 - Writing to a Control Register
In order to read from a control register, the host sends one byte. The byte should be sent more than
200nSec after lowering HDC. The byte begins with the address of the register followed by ”D”H. The
SIG40 will then output the content of the register to pin HDO.
Read Command
Register Address[3:0]
D(hex)
Read Command
Figure 4.4 shows the pins involved in the reading process:
HDC:
T
1
HDI Read
Command:
start bit
0
1
2
3
Address
stop bit
Figure 4.4 - Reading from a Control register
Note: Writing to Register 1
Writing a change frequencies command to register 1 is not always interpreted correctly by the device.
The device will switch to the correct frequencies pair however, it will not function properly, resulting a
communication lost.
Workaround: When changing frequencies by writing to register 1, use the following procedure:
Lower the H_DC.
Send a command to register 1 containing the require frequencies pair and a false bit rate.
Raise the H_DC
Lower the H_DC
Send a command to register 1 containing the require frequencies pair and the required bit rate.
Raise the H_DC.
For example, when wanting to work with frequencies 3.58MHz and 4.5MHz at 19.2Kbps the correct way
to program the device is described in Figure 4.4.1
HDC
HDI
0x15C0
Sending a command
for 3.58MHz/4.5MHz at
38.4Kbps
0x15F0
Sending a command
for 3.58MHz/4.5MHz at
19.2Kbps
Figure 4.4.1 – Writing to Register
Note: Changing only the bit rate can be done with a single write, as described above.
4.4
Loopback
The device operates like a transceiver, therefor while transmitting or writing a command the HDI signal
is looped back to the HDO pin.
@ 2007 Yamar Electronics Ltd.
9
DS-SIG40 R1.8
YAMAR [ YAMAR ELECTRONICS LTD. ]
