******************************************************************
** CHKRX
**
** -Sample program that checks RX pin of serial port
** I show all the UART status bits on these annunciators:
**
** LowBat bRX ( rx pin high, i hope )
** RightShift bRBZ ( receiver busy )
** LeftShift bRBF ( receive buffer full )
** Alpha bRER ( receive error??? )
** IO ( last 0 was a one->zero transition )
**
** - press ON (ATTN) to exit
**
** INPUT: none
**
** OUTPUT: 1: zeroes% ( number of zeroes on RX )
** - this number refers to how many one->zero transitions occurred
**
**
** COMMENTS: try typing quickly to watch the error (alpha) come on
** is you run this with normal serial IO, the RX
** annunciator ((*)) never seems to go off. i don't
** know much about serial IO, but that tells me that
** RX=1 is an idle condition
**
** 10/9/92 - Robert Sanders
** any questions, comments, etc. e-mail to
** pshuprs@prism.gatech.edu or gt8134b@prism.gatech.edu
******************************************************************
ASSEMBLE
NIBASC \HPHP48-E\
** misc UART addresses
CRER EQU #113 ( write here to clear RER )
RBF EQU #114 ( 2-nibble, receive buffer )
** STATUS SERVICE DELAY CONSTANTS
**
** these allow the RER and RBF annunciators and status bits to
** stay set for a while, then be cleared. the numbers are
** #'s of iterations before clearing, and the translation of
** loops->clock cycles->milliseconds will vary slightly with
** your HP48, and also with which bits get set
**
** there is no hardware reason to do this, but you need this
** to see any results.
** the side effect is, a character received isn't taken out of
** the receive buffer for 600 loop iterations (it can easily
** choke at 9600 baud.)
RERCOUNT EQU 600
RBFCOUNT EQU 600
** UART status bits (at addr #111)
bRBF EQU 0 ( receive buffer full )
bRBZ EQU 1 ( receiver busy )
bRER EQU 2 ( receive error? )
bRX EQU 3 ( rx pin high???? )
** UART control bits
bERBZ EQU 0 ( enable interrupt for RBZ? )
bERBF EQU 1 ( enable interrupt for RBF? )
bETBE EQU 2 ( I'd say TransmitBufferEmpty, but dunno )
bSON EQU 3 ( enable UART I/O - SerialON )
** ST bits used
sRER EQU 0
sRBF EQU 1
RPL
*============================================================*
* RPL STARTS HERE *
*============================================================*
::
CLEARVDISP
$ "ALARM ------ RX" DISPROW1
$ "LS: RBF RS: RBZ" DISPROW3
$ "A: RER" DISPROW4
CODE
gosbvl =SAVPTR * save regs
d0=(5) =DISABLE_KBD
la(1) #F
dat0=a 1 * disable keyboard polling (flag)
INTOFF * shut off keyboard interrupts
la(2) #80
d0=(5) =ATTNFLG
dat0=a 1 * init to 0 ON key presses
************************************************************
*********************** ROM INFO *************************
************************************************************
* here's what OpenUartClr at #3161e (PMC) does to setup
* it sets ERBF (enable receive buffer full interrupt?)
* ERBZ (enable receiver busy interrupt?)
* SON (SerialON - enable UART I/O)
*
* d1=(5) #110
* lc(1) #b * sets SON, ERBF, ERBZ
* dat1=c 4
************************************************************
* the following is iffy
d1=(5) =IOC * IOControl register (UART control)
lc(1) 2^bSON * set bSON bit
dat1=c 1
d1=d1+ 1 * serial receive control/status at #111h
d0=(5) =ANNCTRL * annunciator contol (bit 2=ALPHA)
dat0=a 2 * turn all annunciators off, but leave
* enabled (a should be 80 here)
st=0 sRER * no RER condition yet
st=0 sRBF * no RBF condition yet
lc(5) 0
r0=c a
** in this loop, D1 points to the RX status mibb6e
** D0 points to the annunciator control nibble upon
** entry (and loop), but changes
** R0 counts zeroes on RX
** ST<0> indicates RER condition unserviced
** ST<1> indicates RBF condition unserviced
** B holds counter for clearing RER. at b=0, clears
** D holds counter for clearing RBF. at b=0, clears
**
mloop c=dat1 1 * get RX status nibble
?cbit=1 bRX
goyes postzero * after zero processing
** this code does "zero processing"
** if RX=0 last time, the IO annunciator is cleared
** if RX=1 last time, the IO annunciator is set and the zero counter
** is incremented. this flags a one->zero transition
**
** the zero counter is kept in R0
**
a=dat0 1 * get old annunciators
?abit=1 bRX * RX ann was set, so transition occurred
goyes trans
notrans * comes here if RX is zero,
* but RX was zero before
d0=d0+ 1 * point to ANN2
la(1) 8 * ANN_ON=8, IO_ANN=2
dat0=a 1
d0=d0- 1 * point back to ANNCTRL (ANN1)
goto postzero
trans
d0=d0+ 1 * point to ANN2
la(1) 10 * ANN_ON=8, IO_ANN=2
dat0=a 1
d0=d0- 1 * point back to ANNCTRL (ANN1)
a=r0 a * increment 0 counter
a=a+1 a * ..
r0=a a * ..
** post "zero processing"
postzero
dat0=c 1 * drive RX status onto annun.
?cbit#1 bRER * if no RER condition, check RBF
goyes chkrbf
*************** service RER **************
chkrer ?st=1 sRER
goyes cntrer
st=1 sRER * flag the new RER
la(5) RERCOUNT * times to countdown before clearing
b=a a
goto chkrbf
cntrer b=b-1 a * service old RER
?b#0 a
goyes chkrbf * not displayed long enough yet
d0=(5) CRER * address to clear RER
dat0=a 1 * any value will clear
st=0 sRER * mark old RER condition gone
*************** service RBF **************
chkrbf ?cbit#1 bRBF * no RBF condition
goyes chkattn
?st=1 sRBF
goyes cntrbf
st=1 sRBF * flag the new RBF
lc(5) RBFCOUNT * times to countdown before clearing
d=c a
goto chkattn
cntrbf d=d-1 a * service old RBF
?d#0 a
goyes chkattn * not displayed long enough yet
d0=(5) RBF * address of receive buffer
a=dat0 2 * get buffered byte
st=0 sRBF * mark old RBF condition gone
chkattn
d0=(5) =ATTNFLG
c=dat0 1 * get annctrl nibble
?c#0 p * ON pressed yet?
goyes done * exit program
d0=(5) =ANNCTRL
goto mloop
** get us back to the normal system state
done d0=(5) =DISABLE_KBD
la(1) 0
dat0=a 1 * enable keyboard polling
INTON
d1=(5) =IOC * IOControl register (UART control)
lc(1) 0 * clear all, especially bSON
dat1=c 1 * (turn serial I/O off)
gosbvl =GETPTR * restore RPL registers
govlng =PUSH#LOOP * pushes R0 as sysbin and reenter
* RPL main loop
ENDCODE
UNCOERCE ( turn # into real )
;
