Matrix Orbital LK202-24-USB - Manual (Page 28)

Table 14: Example PWM Values for Index =14
Input PWM Actual PWM
0 0
1- 63 25%
64 -127 50%
128 -191 75%
192 -255 100%
Frequencies in the range of 9.6Hz to 38.2Hz are desirable for fan control as they minimize the noise due
to PWM modulation. For visual applications such as controlling cold cathode lights, PWM frequencies of
76.3Hz to 305.2Hz are desirable to minimize flicker.
5.2.7 Remember PWM Base Frequency (254 197 [index])
NOTE This command was added in Firmware Version 2.1. It is not present in previous
versions.
This command will set the PWM frequency for startup. It does not alter the current PWM base frequency.
Refer to the “Set PWM base frequency” command for valid values of index.
6 1-Wire Commands
The 1-wire bus is capable of communicating with many devices over a single wire plus a ground refer-
ence. This chapter deals with the capabilities of the display and a brief introduction to the 1-Wire standard.
For more detail consult www.maxim-ic.com
6.1 Device Identification
Each 1-wire device contains a unique 64-bit address in which to identify them with. The address is
guaranteed to be unique from any other device, allowing a virtually unlimited number of devices on to be
attached to the bus. The address itself contains a family code and a cyclic redundancy check (CRC). The
family code is unique to a particular device model. For example, the family code for the DS18S20 temper-
ature probes is 10H. The CRC byte is included as a verification that the correct address was transmitted or
received.
6.2 Protocol
The transaction sequence for accessing a 1-wire device is as follows;
Matrix Orbital LK202-24-USB 24