The following is a list of frequently asked questions about HLS and CUnet.
Please read the following FAQs before contacting us about products and technologies

FAQ list

HLS Family

CUnet Family

FAQs on CUnet Family under development.

Q&A

	What is the input level of Xi pin when connecting the oscillator to MKY34 or MKY35.
	Input the CMOS level: VIH=3.5V (Min), VIL=1.5V (Max), and lz=±10µA(Max). However, when the load is light, you can use even the oscillator with TTL output, because many parts satisfy the CMOS level input. When connecting the oscillator to Xi, open Xo.
	I'm thinking of using optical communication to use a network in a place having a large electrical potential difference. Give me some advice.
	In the HLS, if full-duplex mode and low speed are selected, you can use optical fiber cable partially.
	Tell me the capability of the error certifications adopted in HLS.
	The HLS uses the CRC12. Its performance is as follows: m=Length of CRC b=Number of error bits When b<=m: 100% When b=m+1: (1-(1/(2m-1)))x100% When b>m+1: (1-(1/(2m)))x100% When the number of error bits is 12 bits or smaller: 100% When the number of error bits is 13 bits: 99.951% When the number of error bits is 14 bits or greater: 99.975% In addition, HLS performs RZ code and format checks simultaneously. Their performance is substantially complete.
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	Di data is always FFFF(H) while HIGH is applied to MKY34 CLR pin. Is there any problem with that?
	It is a feature.
	Give me some advice on cascade connection for MKY34 or MKY35.
	For cascade connection, click Technical report No. 005
	How many nests can be cascade-connected in MKY34 or MKY35?
	For cascade connection, click Technical report No. 005
	Must the satellite addresses assigned to be consecutive numbers?
	No. The system does not require that satellite address must be consecutive numbers. Also, the satellite address need not be physically arranged from a smaller number. However, in order to get higher communication rate, we recommend the satellite address be assigned consecutively because HLS performs polling for satellites from the one with satellite address SA.1 up to the one with the maximum address for the specified number of satellite to be operated.
	If the same address is mistakenly assigned to multiple satellites, how can it be found?
	Check the center's command area. It indicates a permanent communication error has occurred at the terminal to which an incorrect satellite address is assigned (because the terminal where the error occurred does not exist). Check the address of the appropriate terminal.
	I wrote the number of operated satellites to the Start register, but no changes can be found on the HLS memory (and also no data is output from the terminal). When I checked the communication line with the oscilloscope, I could find no communication seems to perform. What is the cause of this?
	Several causes are possible. In most cases, a simple setting mistake (design mistake) is the cause. Check the following: - BPS is (mistakenly) set to EXC, but the clock is not supplied to the EXC pin. - DAEA function is set to be enabled, although the CPU where the DAEA function cannot be used. - DAE pin remains set to HIGH when using the DAE.
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	Tell me how to select a differential driver/receiver?
	Use the driver supporting RS-422 or RS-485 and the baud rate to be used in the system. On the other, select the receiver with high sensitivity for the transmission rate. Even when the catalog spec defines that the receiver sensitivity is 200mVp-p, there may be a case where signal may not be generated normally if about 3Vp-p is not input when the rate is high. - We recommend you evaluate the receiver in advance in the following way: The 12Mbps RZ signal is equivalent to the 6MHz clock when a bit changes most rapidly. So generate the signal (with sine curve or with duty ratio of 50% also available) equivalent to the 6MHz clock with the function generator, etc. and then inputit to the receiver. After this, while reducing the amplitude of the clock by the volume or by splitting resistance, observe until which amplitude level the signal with 50% duty can be regenerated normally on the output side of the receiver. The minimumm signal amplitude at which the signal can be regenerated normally is the input sensitivity of the receiver. (The receiver that can receive data normally even at roughly 300mVp-p or smaller of the sensitivity is recommended. Step Technica uses SN751177 and ADM1485 for our board products)
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	Tell me how to select a oscillator connected to MKY34 or MKY35?
	Both ceramic and crystal oscillators are available if they are within the frequency at which oscillation is possible. The mounted capacitor or resistor varies with the type, maker, and product class of the oscillator, and so refer to [Reference Material] and select a peripheral part to obtain stable oscillation. Oscillation at 4 to 30MHz and 20 to 50MHz are availbale in MKY34 and MKY35, respectively. When other frequencies are used, supply the externally oscillated clock to the XI pin and open the XO pin [Reference material] Technical report No.003, No.004
	How long is the guaranteed transmission distance (unit: m)?
	The rough transmission distance of HLS is 100m for 12Mbps, 200m for 6Mbps, and 300m for 3Mbps, which assume the general use in 32 branched stations (terminals). In addition, these values are greater than those obtained from our experimental result, and in most cases, transmission distances smaller than those are used without being evaluated. However, the transmission distance varies depending on the ambient environment including the cable type, cable setting, number of branched stations, and so on. The above-mentioned values are obtained without taking account of the environment, and we do not always guarantee the transmision distance.
	Can the transmission cable for HLS be extended to about 1km?
	Extending the transmission distance may cause communication error frequently or cause a situation in which no communication can be established. So when extending the transmission distance, evaluate adequately in advance. When trying to extend the transmission distnace about 1km, select a good-quality cable and an appropriate pulse transformer, set a low transmission rate, reduce the number of branches and so on, and evaluate adequately in the actual environment to be used.
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	What kind of CPU can be used in HLS?
	Use the CPU with an 8/16-bit data bus and for which WAIT input is available. Or, use the CPU for which you can insert the wait state to set adequate access time. Both big endian and little endian are supported.
	Now I am evaluating the HLS products, but there are rare occasions when all Do outputs momentarily become LOW (Do data does not change). Is there any problem with that?
	Due to external noise caused by poor mechanical design, noise may get into the signal of CLR pin and this may clear the Do outputs. In order not to be affected by the noise, increase the load capacity by a capacitor. [Reference material] Technical report No. 001
	Can analog data be input or output?
	I/O of the MKY34 is only digital 16 inputs/16 outputs. To use analog data, connect a D/A or A/D converter to the I/O.
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