' Interface de Poursuite- W4SM TrackSM - F1HDI/F1OAT/F5DJL - version 1.1 14/11/2006
' Reception du flux Nova el/az a 4800 bps sur USART sous interruption
' La chaine recue de TrackSM est stockee dans le tableau "chaine_aff"
' 											
Define CONF_WORD = 0x3f3a
Define SEROUT_DELAYUS = 5000
'
'	Declarations variables communes au versions
	Dim i As Byte
	Dim j As Byte
	Dim k As Byte
	Dim l As Byte
	Dim m As Byte
	Dim temp(5) As Byte
	Dim compteur_boucle As Byte
	Dim diff As Word 			'Calcul de difference
	'
	Dim char_cnt As Byte 		'Compteur de character
	'
	Dim chaine_rs(40) As Byte	'Chaine d entree du flux
	Dim chaine_aff(40) As Byte  'Chaine de traitement quand trame recue
	Dim chaine_len As Byte 		'Longeur de la trame recue
'
	Dim valeur_capteur_az As Word  'Valeur ADC 1  AZ brute sur 1024
	Dim valeur_capteur_el As Word  'Valeur ADC 0 EL brute sur 1024 points
	Dim valeur_capteur_az_deg As Word
	Dim valeur_capteur_el_deg As Word
	Dim long_valeur_capteur_az_deg As Long
	Dim long_valeur_capteur_el_deg As Long

	Dim valeur_consigne_az As Word  'Valeur binaire az sans decimale de trame recue
	Dim valeur_consigne_el As Word  'Valeur binaire el sans decimale de trame recue
			
	Dim az_sup As Bit  'A 1 si consigne superieure a valeur
	Dim el_sup As Bit  'A 1 si consigne superieure a valeur
	Dim diff_az As Word
	Dim diff_el As Word
	
	Dim cali_az_min As Word
	Dim cali_az_max As Word
	Dim elevation_horizon_0	As Word

	Dim chaine_recue As Bit 		'Flag de trame complete (0A recu)
	Dim rotor_tracking_az As Bit
	Dim rotor_tracking_el As Bit
	Dim delay_arret As Bit
	Dim az_enable As Bit
	Dim el_enable As Bit
	Dim sortie_cal As Bit

	Dim cali_flag As Byte
	Dim chaine_traitee As Byte  'extraction de az et elevation correcte du RS232

	Dim	cpt_point_el	As Word
	Dim cpt_point_az	As Word

	Dim hysteresis_el As Word  'Hysteresis elevation dans cette version 1/10 deg
	Dim hysteresis_az As Word  'Hysteresis azimut dans cette version 1/10 deg
	Dim consigne_el_max As Word
' ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Pbus section
'
	Symbol pbus_rts = RB1
	Symbol pbus_data = RB2

	Dim pbus_devid As Byte
	Dim pbus_cmd As Byte
	Dim pbus_len As Byte
	Dim pbus_msg(16) As Byte
	Dim pbus_checksum As Byte
	Dim elevation As Word
	Dim pbus_timeout As Bit
	'
'
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'Section  version F5DJL Deltawave
'		Symbol led_boucle = RB5
'		Symbol led_debug = RB4
'		Symbol haut = RB0
'		Symbol bas = RB1
'		Symbol gauche = RB2
'		Symbol droite = RB3

'		Const az_rotor_range = 3600 	' pour 1024 points
'		Const el_rotor_range = 1800		' pour 1024 points
'		Const speed_cw = 150			' duree du point cw led
'		Const relay_on = 50				' duree en ms min de cde on relais
'		Const relay_off = 30				' duree en ms de trainee du relais

'		TRISB = 0x00 				'set all PORTB pins as outputs
' Section version F1HDI Olimex

		Symbol led_boucle = RB4
		Symbol led_debug = RB5
		Symbol haut = RD4
		Symbol bas = RD5
		Symbol gauche = RD6
		Symbol droite = RD7

		Const az_rotor_range = 4500 	' pour 1024 points
		Const el_rotor_range = 900		' pour 1024 points
		Const speed_cw = 150			' duree du point cw led
		Const relay_on = 50				' duree en ms min de cde on relais
		Const relay_off = 30			' duree en ms de trainee du relais

		TRISB = 0x04  'set all PORTB pins as outputs, except RB2 for P-BUS
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'Declarations des Ports

	TRISA = 0xff  'Port a en input
	TRISD = 0x00  'set all PORTD pins as outputs - utilise chez DJL pour pour rotor chez HDI
	PORTD = 0x00  'make all PORTD pins Low
'
'Initialisation port serie
	Hseropen 4800
	WaitMs 250
'
'Initialisation de AN0 et AN1
'
	Define ADC_CLOCK = 2 		'32 Tosc
	Define ADC_SAMPLEUS = 200	'Sampling time 200 microsec
	ADCON1 = 0x04 				'configure AN0 et AN1 input for analog use

' Validation des interruptions sur character recue USART
'
	PIE1.RCIE = 1 		'enable usart receive interrupt
	INTCON.PEIE = 1 	'enable all un-masked peripheral interrupt
	INTCON.GIE = 1 		'enable all un-masked interrupts
'
' Debut du programme
'
main:
' Affichage pendant 1 s led au demarrage
	Call trait_cw()
	WaitMs 500
	Call read_eeprom()
	Call led_k()

	Select Case cali_flag
		Case 1
		valeur_consigne_az = 0
		valeur_consigne_el = 0
		consigne_el_max = 870
			
		Case 2
		valeur_consigne_az = 0
		valeur_consigne_el = 0

	Else
		valeur_consigne_az = 0
		valeur_consigne_el = 0
		cali_az_max = 1023
		cali_az_min = 0
		elevation_horizon_0	 = 1780
		consigne_el_max = 870
		hysteresis_el = 15  'Hysteresis elevation dans cette version 1/10 deg
		hysteresis_az = 10  'Hysteresis azimut dans cette version 1/10 deg

		Call trait_cw()
	EndSelect
	
	WaitMs 1000

' Initialisation des variables
	char_cnt = 0
	chaine_recue = 0
	chaine_traitee = 3

	cpt_point_az = 0
	cpt_point_el = 0

	az_enable = 1
	el_enable = 1

	rotor_tracking_az = 0
	rotor_tracking_el = 0
	sortie_cal = 0
	
	compteur_boucle = 1
	delay_arret = 0

	For i = 1 To 40
		chaine_rs(i) = 0
		chaine_aff(i) = 0
	Next i

	Call arret_az()
	Call arret_el() 		

'Debut de la routine de boucle principale
	
main_loop:
'
		Toggle led_boucle 	' Visibilise l' activite boucle principale
		
		WaitMs 200
' 		''''''''''''''''''''''''''''''Routine traitement chaine ascii recue '''''''''''
		
		If chaine_recue = 1 Then
			Call traitement_chaine()
			chaine_recue = 0
		Endif

'		''''''''''''''''''''''''''''''Routine Traitement des park speciaux ''''''''''''''		
		If chaine_traitee = 1 Then
			Select Case valeur_consigne_az
				Case 6390					' parking active 999 (6390 transmis)
					Call calibration_az()
					sortie_cal = 1
				Case 5100					' parking active a 870 (5100 transmis)
					Call calibration_hor_el()
					sortie_cal = 1	
				Case 5200					' parking active a 880 (5200 transmis)
					Call hysteresis_az()
					sortie_cal = 1	
				Case 5300					' parking active a 890 (5300 transmis)
					Call hysteresis_el()
					sortie_cal = 1
				Case 5000					' parking active a 860 (5000 transmis)
					Call init_eeprom() 	
					sortie_cal = 1	
			EndSelect
			If sortie_cal = 1 Then
			rotor_tracking_az = 0
			rotor_tracking_el = 0
			chaine_traitee = 0
			sortie_cal = 0
			Endif

		Endif
		
'		''''''''''''''''''''''Routine pointage Elevation ''''''''''''''''''''''''''''''''		'
		If el_enable = 1 And rotor_tracking_el = 1 Then
			
				Call diff_elevation()
				
				If valeur_consigne_el < consigne_el_max Then

					If diff_el > hysteresis_el Then
						cpt_point_el = cpt_point_el + 1
'						Hserout "#pointage EL", #cpt_point_el, CrLf
					Endif

					While diff_el > hysteresis_el 		
						Select Case el_sup
							Case 0
								Call descendre()
								WaitMs relay_on
								delay_arret = 1
							Case 1
								Call monter()
								WaitMs relay_on
								delay_arret = 1
						EndSelect
					Call diff_elevation() 	
					Wend
				Endif
				
				'sortie_el:
				If delay_arret = 1 Then
					WaitMs relay_off				'Motor trainée
					delay_arret = 0
				Endif	
		
				Call arret_el()
				rotor_tracking_el = 0
					
		Endif
'		'''''''''''''''''''' Pointage Azimut ''''''''''''''''''''''''''''''''
		If az_enable = 1 And rotor_tracking_az = 1 Then

			Call diff_azimut()

			While diff_az > hysteresis_az 		
				Select Case az_sup
					Case 0
						Call tourner_gauche()
						WaitMs relay_on
						delay_arret = 1
					Case 1
						Call tourner_droite()
						WaitMs relay_on
						delay_arret = 1
				EndSelect
				Call diff_azimut()
			Wend
			sortie_az:
				If delay_arret = 1 Then
					WaitMs relay_off			'Motor trainée
					delay_arret = 0
				Endif	
			Call arret_az()
			rotor_tracking_az = 0

		Endif

'		'''''''''''''''''''''Routine Affichage ''''''''''''''''''''''''''''''''


		If compteur_boucle = 1 Then
			Call diff_azimut()
			Call diff_elevation()

			Gosub affichage_rs232 		'Affichage consignes et capteurs vers RS 232
			compteur_boucle = 100
			Else		
			compteur_boucle = compteur_boucle - 1
			Endif
		
		chaine_traitee = 3
		
		Goto main_loop
	End
'
'			Routine Affichage RS232
affichage_rs232:

	Hserout 27, 91, 50, 74, CrLf

	Hserout " J79DI- Moon Tracker version 1.1 - ", CrLf, CrLf
	Hserout " Capteur     AZ: ", #valeur_capteur_az_deg, "               EL:  ", #valeur_capteur_el_deg, CrLf
	Hserout " Consigne    AZ: ", #valeur_consigne_az, "                 EL:  ", #valeur_consigne_el, CrLf
	Hserout " Difference  AZ: ", #diff_az, "   Difference El :  ", #diff_el, CrLf, CrLf
	Hserout " Calibration Az_max : ", #cali_az_max, "        Az_min :  ", #cali_az_min, "       Horizon cal  :", #elevation_horizon_0, CrLf,
	Hserout " Hysteresis Az : ", #hysteresis_az, "        Hysteresis El:  ", #hysteresis_el, CrLf
	Hserout " Range El max  :", #consigne_el_max, "    Flag Calibration: ", #cali_flag, CrLf, CrLf
Return
' Routine interruption sur character recu RS232
	On Interrupt  'interrupt routine
	Save System  'sauvegarde contexte
'

	If char_cnt < 40 Then 		'Protection contre flux > 40 characters
		char_cnt = char_cnt + 1
		Else
		char_cnt = 0
	Endif
'
loop_rs:
	Hserget l  'Character valide dans chain_rs(char_cnt)
	If l > 0 Then
		chaine_rs(char_cnt) = l
		Toggle led_debug
	Else
	Goto loop_rs
	Endif
'
		If chaine_rs(char_cnt) = 10 Then  ' Si LF recu alors transfer de la chaine dans chaine_aff
			chaine_len = char_cnt
			For m = 1 To chaine_len
				chaine_aff(m) = chaine_rs(m)
			Next m
			chaine_recue = 1	' flag de chaine recue
			Low led_debug
			char_cnt = 0 		' RAZ compteur character
		Endif
	PIR1.RCIF = 0  'enable new usart interruption
Resume

Proc traitement_chaine()

' Routine de traitement de la chaine recue
		' lit la chaine recue identifie A et E pour extraction de la
		' valeur binaire de AZ :az et EL :el ainsi que la partie entiere
		' dans valeur_consigne_az et valeur consigne_el
		'
		traitement_chaine:
		'
		chaine_traitee = 3
		For i = 1 To chaine_len  'lit la chaine
			Select Case chaine_aff(i)
			Case 65  'si A trouvee calcul de az
				k = 1
				j = i + 3  'initialise k et jump apres ":"
				chaine_traitee = chaine_traitee - 1 		' "A" de AZ  identifie
			boucle_az:
			Select Case chaine_aff(j)
				Case 46  'si char = "."
					Goto decimale_az  'traitement decimale
				Case 32  'si " " fin de chaine
					Goto fin_az
				Case Else  'autre cas charge digit ascci dans temp(k)
					temp(k) = chaine_aff(j)
					j = j + 1
					k = k + 1  'incremente pointeur temp
				EndSelect
			Goto boucle_az
			decimale_az:
				j = j + 1  'incremente lecture chaine (saut du point)
			Goto boucle_az
			fin_az: 	'calcul de la valeur decimale 299.6 =2996
			valeur_consigne_az = asc2bin(temp(1), temp(2), temp(3), temp(4), k)
'
'
			Case 69  'si E trouve clacul de el
				k = 1
				j = i + 3  'initialise k et jump apres ":"
				chaine_traitee = chaine_traitee - 1 		' "E" de EL  identifie
			boucle_el:
			Select Case chaine_aff(j)
				Case 46  'si char = "."
					Goto decimale_el  'traitement decimale
				Case 13, 32  'si cr ou " " fin de chaine
					Goto fin_el
				Case Else  'autre cas charge digit ascci dans temp(k)
					temp(k) = chaine_aff(j)
					j = j + 1
					k = k + 1  'incremente pointeur temp
				EndSelect
			Goto boucle_el
			decimale_el:
				j = j + 1  'incremente lecture chaine (saut du point)
			Goto boucle_el
			fin_el:  'calcul de la valeur decimale 85.1 = 851
			valeur_consigne_el = asc2bin(temp(1), temp(2), temp(3), temp(4), k)
		EndSelect
	Next i
	rotor_tracking_az = 1
	rotor_tracking_el = 1

End Proc

Proc diff_azimut()

			valeur_capteur_az = adc_read_filt(1)
		
			long_valeur_capteur_az_deg = (az_rotor_range * (valeur_capteur_az - cali_az_min)) / (cali_az_max - cali_az_min)
			valeur_capteur_az_deg = long_valeur_capteur_az_deg.LW

			If valeur_consigne_az > valeur_capteur_az_deg Then
					diff_az = valeur_consigne_az - valeur_capteur_az_deg
					az_sup = 1
			Else
					diff_az = valeur_capteur_az_deg - valeur_consigne_az
					az_sup = 0
			Endif

End Proc
Proc diff_elevation()
			
		Call request_pbus_elevation()
		Call read_pbus_elevation() 		' Result in elevation and pbus_timeout
		WaitMs 	200						

		If pbus_timeout = 0 Then
			valeur_capteur_el = elevation - elevation_horizon_0	
			long_valeur_capteur_el_deg = (el_rotor_range * valeur_capteur_el) / 1024
			valeur_capteur_el_deg = long_valeur_capteur_el_deg.LW
		
			If valeur_consigne_el > valeur_capteur_el_deg Then
				diff_el = valeur_consigne_el - valeur_capteur_el_deg
				el_sup = 1
			Else
				diff_el = valeur_capteur_el_deg - valeur_consigne_el
				el_sup = 0
			Endif
		Endif
End Proc
'
Proc arret_az_el()  'arrêt des moteurs
	Call arret_az()
	Call arret_el()
End Proc
'
Proc arret_az()  'arrêt moteur d'azimut
	Low droite
	Low gauche
End Proc
'
Proc tourner_gauche()  'tourner à gauche
	Low droite
	High gauche
End Proc
'
Proc tourner_droite()  'tourner à droite
	Low gauche
	High droite
End Proc
'	Arrêt moteur de site
Proc arret_el()
	Low bas
	Low haut
End Proc
'	Monter moteur de site
Proc monter()
	Low bas
	High haut
End Proc
'	Descendre moteur de site
Proc descendre()
	Low haut
	High bas
End Proc
'
' Fonction de lecture de l ADC (parametre 0 ou 1) et moyenne sur 5 echantillons
'
Function adc_read_filt(arg1 As Byte) As Word

	Dim v(5) As Word
	Dim vm As Word
	PIE1.RCIE = 0				' disable interrupt RS232
	For i = 0 To 4				' Acquisition de 5 valeurs
		Adcin arg1, v(i)
	Next i
	vm = 0
	For i = 0 To 4				' Calcul moyenne des 5 lectures
		vm = vm + v(i)
	Next i
	vm = vm / 5					'
	adc_read_filt = vm
	PIE1.RCIE = 1				' enable interrupt RS232

End Function

' Routine Lecture dans l EEPROM
Proc read_eeprom()
		Read 0, cali_flag
		Read 1, cali_az_max.HB
		Read 2, cali_az_max.LB
		Read 3, cali_az_min.HB
		Read 4, cali_az_min.LB
		Read 5, elevation_horizon_0.HB
		Read 6, elevation_horizon_0.LB
		Read 7, hysteresis_az.HB
		Read 8, hysteresis_az.LB
		Read 9, hysteresis_el.HB
		Read 10, hysteresis_el.LB
End Proc

'Fonction de conversion ascii 5 characters max en binaire (max 9999 , arg 5 = nb de digit inclus decimale))
'
Function asc2bin(arg1 As Byte, arg2 As Byte, arg3 As Byte, arg4 As Byte, arg5 As Byte) As Word
Select Case arg5
	Case 3
		arg1 = arg1 - 48
		arg2 = arg2 - 48
		asc2bin = (arg1 * 10) + arg2
	Case 4
		arg1 = arg1 - 48
		arg2 = arg2 - 48
		arg3 = arg3 - 48
		asc2bin = ((arg1 * 100) + (arg2 * 10) + arg3)
	Case 5
		arg1 = arg1 - 48
		arg2 = arg2 - 48
		arg3 = arg3 - 48
		arg4 = arg4 - 48
		asc2bin = ((arg1 * 1000) + (arg2 * 100) + (arg3 * 10) + arg4)
EndSelect
End Function
'
'Fonction valeur absolue d' un nombre signé sur un WORD
'
Function abs(arg1 As Word) As Word
	If arg1 > 32768 Then
		abs = Not arg1
		abs = abs + 1
	Else
		abs = arg1
	Endif
End Function
' Routine clignotement k sur led_boucle
Proc led_k()
	Call trait_cw()
	Call point_cw() 		
	Call trait_cw()
	Call space_cw()
End Proc
Proc trait_cw() 	
	Dim trait_cw As Word
	trait_cw = 3 * speed_cw
	High led_boucle
	WaitMs trait_cw
	Low led_boucle
	WaitMs speed_cw
End Proc
Proc point_cw()
	High led_boucle
	WaitMs speed_cw
	Low led_boucle
	WaitMs speed_cw
End Proc
Proc space_cw()
	Dim space_cw As Word
	space_cw = 3 * speed_cw
	WaitMs space_cw
End Proc
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'
'		Section routine Calibration invoques paz des valeurs particuliere
'				des consignes azimut via une commande park
'		1/ Calibration horizontale : Park a l' azimut 999
'		2/ Calibration de l'offset vertical (valeur absolue du capteur a el=0) : Park 510
'		3/ Effacement de la memoire EEPROM addresse 0 pour utilisation des valeurs hardcodees
'		Dans tous les cas attendre fin de procedure signalee paz "AZ K" "EL K" ou "EE K" sur
'		LED et console et retour en attente de commande ( attention si le park est maintenue
' 		la procedure recommence !!!
''
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Proc calibration_az()

Dim min As Word
Dim minp As Word
Dim max As Word
Dim maxp As Word

	Call arret_az()
	Call arret_el()

	minp = 1024 						'max range
	min = adc_read_filt(1)
	If min > 0 Then
		Call tourner_gauche()
		While minp > min
				minp = min
				WaitMs 1000
				min = adc_read_filt(1)
		Wend
	Endif
	Call arret_az()
	cali_az_min = min

	maxp = 0 				'min range
		max = adc_read_filt(1)
	If max < 1024 Then
		Call tourner_droite()
		While max > maxp
			maxp = max
			WaitMs 1000
			max = adc_read_filt(1)
		Wend
	Endif
				
	Call arret_az()
	cali_az_max = max
	Call arret_el()
'
'routine ecriture dans l EEPROM
	
		Write 0, 1
		Write 1, cali_az_max.HB
		Write 2, cali_az_max.LB
		Write 3, cali_az_min.HB
		Write 4, cali_az_min.LB
		
	WaitMs 250

	Call led_k()
	
	WaitMs 1000

	Call read_eeprom()

	Call led_k()

	End Proc

Proc calibration_hor_el()

		Call request_pbus_elevation()
		Call read_pbus_elevation() 		' Result dans elevation and pbus_timeout
		
		If pbus_timeout = 0 Then
			elevation_horizon_0	 = elevation + 10
			Write 0, 2
			Write 5, elevation_horizon_0.HB
			Write 6, elevation_horizon_0.LB
		Endif
'
		Call led_k()
		Call read_eeprom()

	Hserout " Calibration Elevation terminee ", CrLf
	Hserout " valeur du capteur a el=0 ", #elevation, CrLf, CrLf
	WaitMs 1000

End Proc

Proc hysteresis_az()

	hysteresis_az = valeur_consigne_el

' Routine ecriture dans l EEPROM

		Write 7, hysteresis_az.HB
		Write 8, hysteresis_az.LB

	Call led_k()
	
	Call read_eeprom()

	Hserout " Hysteresis az :", #hysteresis_az, CrLf, CrLf

	WaitMs 1000

End Proc

Proc hysteresis_el()
	
	hysteresis_el = valeur_consigne_el

' Routine ecriture dans l EEPROM

		Write 9, hysteresis_el.HB
		Write 10, hysteresis_el.LB
	
	Call led_k()

	Call read_eeprom()

	Hserout " Hysteresis el :", #hysteresis_el, CrLf, CrLf

	WaitMs 1000

End Proc

' Routine Initialisation eeprom
Proc init_eeprom()

		cali_flag = 1
		cali_az_max = 1023
		cali_az_min = 0
		elevation_horizon_0	 = 1780
		hysteresis_el = 15  'Hysteresis elevation dans cette version 1/10 deg
		hysteresis_az = 10  'Hysteresis azimut dans cette version 1/10 deg

		Write 0, cali_flag
		Write 1, cali_az_max.HB
		Write 2, cali_az_max.LB
		Write 3, cali_az_min.HB
		Write 4, cali_az_min.LB
		Write 5, elevation_horizon_0.HB
		Write 6, elevation_horizon_0.LB
		Write 7, hysteresis_az.HB
		Write 8, hysteresis_az.LB
		Write 9, hysteresis_el.HB
		Write 10, hysteresis_el.LB

	WaitMs 100

	Call read_eeprom()

	WaitMs 1000

End Proc


''''''''''''''''''''''''''''''''''''''''''''''''''''
'
'
'			Routines P-Bus F1OAT Novembre 2006
'
'
'''''''''''''''''''''''''''''''''''''''''''''''''''''
' Lecture de l elevation et mise dans elevation (WORD)

Function read_pbus_elevation() As Byte
	' Wait for RECHO answer
	Call recv_pbus_msg()
	elevation.HB = pbus_msg(0) 			'Unit is 1/16 deg
	elevation.LB = pbus_msg(1)
End Function

' Demande de l elevation pbus

Proc request_pbus_elevation()
	' Send CPING command
	High pbus_rts	' put ADM483 in tx
					' send cping frame To device #1
	Low pbus_data
	WaitMs 2  '5 Test
	SeroutInv pbus_data, 2400, 0x10, 0x5f, 0x91	
	WaitMs 2  '5 Test
	High TRISB.2	' put back RB2 to input before ADM483 RX
	Low pbus_rts	' Put ADM483 in RX
End Proc

' Lecture avec timeout de in pbus

Function serin_timeout(serin_cpt As Word) As Byte
	While serin_cpt > 0
		If pbus_data Then
			SerinInv pbus_data, 2400, serin_timeout
			Exit
		Endif
		serin_cpt = serin_cpt - 1
	Wend
	pbus_timeout = 1
	serin_timeout = 0
End Function

' Reception P-Bus  message

Proc recv_pbus_msg()
	Dim devid_len As Byte
	pbus_timeout = 0

wait_pbus:
	'Serin pbus_data, 2400, devid_len, pbus_cmd	' wait For P-bus packet header

	devid_len = serin_timeout(50000)
	pbus_cmd = serin_timeout(1000)

	pbus_checksum = devid_len + pbus_cmd
	pbus_len = devid_len And 0x0f
	pbus_devid = devid_len / 16
	For i = 0 To pbus_len
		pbus_msg(i) = serin_timeout(1000)
		pbus_checksum = pbus_checksum + pbus_msg(i)
	Next i
	If pbus_checksum <> 0 And pbus_timeout = 0 Then Goto wait_pbus				' corrupted packet
End Proc