Atmel SpW-10X user manual TX 10MbitDIV +1, Setting SpaceWire Transmit Data Rate

SpW-10X	Ref.:	UoD_SpW-10X_
SpaceWire Router		UserManual
	Issue:	3.4
User Manual
	Date:	11th July 2008

	⎛	⎛	(100MHz + (20MHz * FEEDBDIV ))⎞ ⎞
	⎜	⎜		⎟ ⎟
			2TXDIV +1
10MbitRate =	⎜	⎝		⎠ ⎟		* 2
	⎜				⎟
			TX10MbitDIV +1
	⎜				⎟
	⎝				⎠

To provide a SpaceWire signal with a nominal 50/50 duty cycle, TXRATE and TX10MbitDIV should be even integers.

Not all values of FEEDBDIV, TXDIV and TXRATE give valid clock signals. Table 8-1shows the recommended values to use to achieve a range of SpaceWire transmit data rates.

				Table 8-1 Setting SpaceWire Transmit Data Rate
FEEDBDIV	TXDIV	TX10MBITDIV					TXRATE							Initialisation
														Rate	Cycle
														Data Rate
			0	1	2	3	4	5	6	7	8	9	10	Data	Duty
			[1:1]	[1:3]	[1:1]	[3:5]	[1:1]	[5:7]	[1:1]	[7:9]	[1:1]	[9:11]	[1:1]
5	0	19	200.0	100.0	66.67	50.0	40.0	33.33	28.57	25.0	22.22	20.0	18.18	10.000	[19:21]
4	0	17	180.0	90.0	60.0	45.0	36.0	30.0	25.71	22.5	20.0	18.0	16.36	10.000	[17:19]
3	0	15	160.0	80.0	53.33	40.0	32.0	26.67	22.86	20.0	17.78	16.0	14.55	10.000	[15:17]
2	0	13	140.0	70.0	46.67	35.0	28.0	23.33	20.0	17.5	15.56	14.0	12.73	10.000	[13:15]
1	0	11	120.0	60.0	40.0	30.0	24.0	20.0	17.14	15.0	13.33	12.0	10.91	10.000	[11:13]
0	0	9	100.0	50.0	33.33	25.0	20.0	16.67	14.29	12.5	11.11	10.0	9.09	10.000	[9:11]
5	1	9	100.0	50.0	33.33	25.0	20.0	16.67	14.29	12.5	11.11	10.0	9.09	10.000	[9:11]
4	1	8	90.0	45.0	30.0	22.5	18.0	15.0	12.86	11.25	10.0	9.0	8.18	10.000	[1:1]
3	1	7	80.0	40.0	26.67	20.0	16.0	13.33	11.43	10.0	8.89	8.0	7.27	10.000	[7:9]
2	1	6	70.0	35.0	23.33	17.5	14.0	11.67	10.0	8.75	7.78	7.0	6.36	10.000	[1:1]
1	1	5	60.0	30.0	20.0	15.0	12.0	10.0	8.57	7.5	6.67	6.0	5.45	10.000	[5:7]
0	1	4	50.0	25.0	16.67	12.5	10.0	8.33	7.14	6.25	5.56	5.0	4.55	10.000	[1:1]
5	2	4	50.0	25.0	16.67	12.5	10.0	8.33	7.14	6.25	5.56	5.0	4.55	10.000	[1:1]
4	2	4	45.0	22.5	15.0	11.25	9.0	7.5	6.43	5.63	5.0	4.5	4.09	9.000	[1:1]
3	2	3	40.0	20.0	13.33	10.0	8.0	6.67	5.71	5.0	4.44	4.0	3.64	10.000	[3:5]
2	2	2	35.0	17.5	11.67	8.75	7.0	5.83	5.0	4.38	3.89	3.5	3.18	11.667	[1:1]
1	2	2	30.0	15.0	10.0	7.5	6.0	5.0	4.29	3.75	3.33	3.0	2.73	10.000	[1:1]
0	2	2	25.0	12.5	8.33	6.25	5.0	4.17	3.57	3.13	2.78	2.5	2.27	8.333	[1:1]

In Table 8-1 the values with a white background are the values that should be used. The ones in red/shaded should not be used.

The first three columns give settings for the FEEDBDIV pins on the SpW-10X device, the TXDIV field in the transmit clock register (see section 9.5.9) and the TX10MbitDIV field also in the transmit clock register.

Preliminary 83