Hi,
This is probably one for Seb (sorry!).
I'm using 18F4620 with jal 2.4n
I think I've found a bug with the adc_channels setup:
18F4620 uses fixed assignments for ADC channels (using ADCON1_PCFG)
and you can optionally change two channels (AN2&AN3) to Vref+ and
Vref- using ADCON1_VCFG.
adc_channels:
-- -----------------------------------------
-- FIRST CASE:
-- - PCFG bits exist,
-- - analog are dependent from each other
-- - Vref config is done via PCFG bits
-- combination
-- -----------------------------------------
this is not correct for the 18F4620, as Vref config is done using VCFG
further down the code loads ADC_PCFG_MAP:-
if target_chip == PIC_18F4525 | target_chip == PIC_18F4620 then
-- This array stores PCFG config bits, 3 by 3, for each
number of
-- ADC channels, from 1 to the max:
-- For each 3-tuple: (no vref, 1 vref, 2 vref)
const byte ADC_PCFG_MAP [42] = {0b_1111, 0b_0, 0b_0, 0b_1110,
0b_0, 0b_0, 0b_1101, 0b_0,......}
var bit*4 no_vref = 0
var bit*4 one_vref = 0
var bit*4 two_vref = 0
if (ADC_NCHANNEL) == 0 then
asm nop
elsif (ADC_NCHANNEL) == 1 then
pin_AN0_direction = input
elsif (ADC_NCHANNEL) == 2 then
pin_AN1_direction = input
pin_AN0_direction = input
...
...
...
end if
end if
and at the end of that section:-
-- Vref configuration via PCFG bits are directly linked to the
"if" hell just above,
-- some variable/contant exist and are defined specifically
depending on the PICs.
-- pin setup and vref setup can't be dissociated in the context,
this is why this
-- Vref setup is included in pin setup procedure
-- Retrieve config bits according to selected number of ADC
channels
-- ADC_PCFG_MAP contains all confs, from 0 analog to the max
if defined(ADC_DYNAMIC) == true then
var byte idx = ADC_NCHANNEL * 3
else
const byte idx = ADC_NCHANNEL * 3
end if
if ADC_NVREF == 0 then
no_vref = ADC_PCFG_MAP[idx]
ADCON1_PCFG = no_vref
elsif ADC_NVREF == 1 then
one_vref = ADC_PCFG_MAP[idx + 1]
ADCON1_PCFG = one_vref
elsif ADC_NVREF == 2 then
two_vref = ADC_PCFG_MAP[idx + 2]
ADCON1_PCFG = two_vref
else
-- This is only valid when using constant, ie. not dynamic
ADC channels
if defined(ADC_DYNAMIC) == false then
_error "You can't have more than 2 VRef..."
end if
end if
end procedure
based on the above if ADC_NCHANNEL is not equals to 0 (ie Vref
channels required) then 0b_0 will be loaded into ADCON1_PCFG (which on
the 18F4620 sets ALL anaologue channels on!) - ie ADC_PCFG_MAP values
are not correct.
a bit further down (still under "First Case"):-
-- declare dummy procedure for normalization. Note Vref setup, due
to some jalv2 contraints
-- (like defining a constant but assigning its definitive value
later), Vref setup is done
-- while discovering/setting up ADC pins. See comment within
_adc_setup_pins() for dependent pins
procedure _adc_vref() is
end procedure
this means that you can't select Vref using VCFG.
Cheers, Noel.
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