HadCon 2 Multipurpose Controls Performance

Introduction

Theoretical limits

• The current firmwares (up to 4.6.2) all run at 10 MHz HadCon2 clock and
  have 115200 kBits/s at the UART with 8N1 setting
• Thus a long message of 100 Byte (maximum 140 Byte) would need at least:
  
  
  
  

  Message Length [Byte]	approx. Duration [ms]	max. Frequency [Hz]	comment
  140	10.9	91	max. message size incl. CR and LF
  100	7.8	128
  25	1.95	512	e.g. APFEL 9 300 3 1 1 A 1\r\n
  12	0.94	1067	e.g. RGWR 2c f0\r\n

• possible improvements:
  • 10 MHz ⇒ 16 MHz would allow Bitrates up to 1 MBaud, i.e.
    

    Message Length [Byte]	approx. Duration [ms]	max. Frequency [Hz]	comment
    140	1.26	793.7	max. message size incl. CR and LF
    100	0.9	1111
    25	0.225	4444	e.g. APFEL 9 300 3 1 1 A 1\r\n
    12	0.108	9259	e.g. RGWR 2c f0\r\n

Rate stability - RGWR toggle I/O port

Setup

• HadCon2
  • Firmware Version: 4.6.3.APFEL May 27 2015 15:52
  • 115200 kBit/s
  • 10 MHz Clock
• Raspberry Pi B (1)
• EPICS
  • base3.14.12.4
  • streamDevice-2-6
  • asyn4-23
  • application:
    • calcout Record using streamDevice and the protocol File RGWR.proto to send:
      RGWR <register address> <value>
    • modified menuScan.dbd ⇒ menuScanFast.dbd to provide faster scan rates up to 1000kHz.
    • hadcon2_RGWR_test.tar.bz2

Procedures

1. toggle:
   By sending RGWR 2c 80, i.e. the PINE register, the 8^th pin (PE7) on PORT E which is connected partly to HadCon2's connector JAtmelMisc1, pin no. 8, is toggling its state.
   Connected to an oscilloscope the response - an rectangular pulse train - is measured. Two scenarios are measured:
   • normal operation of the IOC
   • slowed down by streamDevice debug printouts - var streamDebug 1
   Example:
2. By sending alternatingly RGWR 2e 80 or RGWR 2e 0, i.e. the PORTE register, the 8^th pin (PE7) on PORT E which is connected partly to HadCon2's connector JAtmelMisc1, pin no. 8, is actively written 0/1 to.
   Connected to an oscilloscope the response - an rectangular pulse train - is measured.

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Measurements

• RGWR-perfomance-toggle.xlsx: Excel Sheet Measurements

Data: toggle

EPICS SCAN rate	Freq [Hz] (1/SCAN)	ideal width	w/o streamDebug output							w/ streamDebug printouts
			Freq [Hz] of 2 Triggers	W: averaged signal width [ms]	ΔW [ms]	ΔW/W	width ratio averaged/ideal	Lost Triggers/Triggers	relative Loss	Freq [Hz] of 2 Triggers	W: averaged signal width [ms]	ΔW [ms]	ΔW/W	width ratio averaged/ideal	Lost Triggers/Triggers	relative Loss
2.00	0.50	2000	0.250	2000.0	80	4.0%	1.00	0/50	0.0%	0.25	2000	85	4.3%	1.0	0/25	0.0%
1.00	1.00	1000	0.500	1000.0	40	4.0%	1.00	0/50	0.0%	0.5	1000	40	4.0%	1.0	0/25	0.0%
0.50	2.00	500	1.000	500.1	35	7.0%	1.00	0/50	0.0%	1	500	21	4.2%	1.0	0/11	0.0%
0.20	5.00	200	2.500	200.0	10	5.0%	1.00	0/50	0.0%	2.475	202	13	6.4%	1.0	0/25	0.0%
0.15	6.67	150	3.378	148.0	5	3.4%	0.99	0/67	0.0%	3.333	150	9	6.0%	1.0	0/17	0.0%
0.1	10.00	100	5.000	100.0	6	6.0%	1.00	0/50	0.0%	2.5	200	4	2.0%	2.0	13/25	52.0%
0.05	20.00	50	10.000	50.0	3	6.0%	1.00	0/50	0.0%	3.378	148	5	3.4%	3.0	13/20	65.0%
0.04	25.00	40	12.500	40.0	4	10.0%	1.00	0/63	0.0%	4.348	115	5	4.3%	2.9	17/25	68.0%
0.033	30.30	33	14.900	33.6	3	8.9%	1.02	0/76	0.0%	3.9	128	12	9.4%	3.9	22/30	72.6%
0.025	40.00	25	20.160	24.8	1	4.0%	0.99	0/21	0.0%	4.032	124	10	8.1%	5.0	32/40	80.0%
0.015	66.67	15	32.900	15.2	1	6.6%	1.01	0/67	0.0%	3.8	132	2	1.5%	8.8	58/67	87.0%
0.014	71.43	14	35.720	14.0	3.5	25.0%	1.00	3.5/72	4.9%	4.6	109	5	4.6%	7.8	62/71	86.8%
0.013	76.92	13	25.300	19.8	8	40.5%	1.52	23/100	23.0%	4.2	119	1	0.8%	9.2	68/77	88.4%
0.012	83.33	12	20.830	24.0	3	12.5%	2.00	52/105	49.5%	4.1	122	2	1.6%	10.2	74/83	88.8%
0.011	90.91	11	23.000	21.7	1	4.6%	1.98	44/90	48.9%
0.01	100.00	10	24.500	20.4	0.5	2.5%	2.04	50/100	50.0%
0.0075	133.33	7.5	33.800	14.8	2	13.5%	1.97	33/66	50.0%
0.005	200.00	5	33.330	15.0	2	13.3%	3.00	67/100	67.0%
0.004	250.00	4	31.200	16.0	2	12.5%	4.01	93/125	74.4%
0.003	333.33	3	33.000	15.2	2	13.2%	5.05	133/166	80.1%
0.002	500.00	2	32.900	15.2	1	6.6%	7.60	267/333	80.2%
0.001	1000	1	breakdown of communication via UART, close to theoretical limit of ≈ 1kHz

Data: set/reset

EPICS SCAN rate	Freq [Hz] (1/SCAN)	ideal width	Freq [Hz] of 2 Triggers	W: averaged signal width [ms]	ΔW [ms]	ΔW/W	width ratio averaged/ideal	Lost Triggers/Triggers	relative Loss
1,00	1,00	1000	0,500	1000,0	10	1,0%	1,00	0/10	0,0%
0,50	2,00	500	1,000	500,0	22	4,4%	1,00	0/50	0,0%
0,20	5,00	200	2,500	200,0	10	5,0%	1,00	0/50	0,0%
0,15	6,67	150	3,200	156,3	15	9,6%	1,04	0/60	0,0%
0,10	10,00	100	5,000	100,0	5	5,0%	1,00	0/100	0,0%
0,03	30,30	33	15,430	32,4	0,4	1,2%	0,98	0/30	0,0%
0,03	40,00	25	20,000	25,0	1,5	6,0%	1,00	0/100	0,0%
0,02	66,67	15	33,330	15,0	1,1	7,3%	1,00	3/166	1,8%
0,01	71,43	14	35,715	14,0	1	7,1%	1,00	14/71	19,7%
0,01	76,92	13	37,600	13,3	1	7,5%	1,02	30/76	39,5%
0,01	83,33	12	10,000	50,0	5	10,0%	4,17	194/208	93,3%

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Results

RGWR toggle performance:


• For a simple toggling register, the maximum frequency is between:
  • 66.67 Hz and 71.43 Hz.
  • Thus the recommendation is to stay above a corresponding EPICS SCAN time of:
    • 0.015s
• If any streamDebug features are active, i.e. print outs to screen, the performance is reduced by:
  • a factor of 10
• at higher SCAN rates up to 80% of the toggle signals are lost, but the system is still performing, since the commands are always the same.
  • in those cases the ratios show that the actual scan time is scaled up.
  • other cases have not been investigated
  • RGWR toggle performance ratios:
    
• finally at a rate of 1kHz, the system reaches is limit and the communication to the board ceases, but can be recovered.

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RGWR set/reset performance:


• For a set/reset register, the maximum frequency is at around:
  • 60 Hz.
  • Thus the recommendation is to stay above a corresponding EPICS SCAN time of:
    • 0.017s

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