DM-15CC

DM-15CC - a real HP 15C clone

Front view and its font

Smooth font
Firmware = DM15CC_MEM80_V8 Slim font
Firmware = DM15CC_S_V10

Internal view

(NXP LPC1115F/303 12MHz, SILABS CP2012DCL0Y5, C6=100uF)

Note *1 : There is a possibility of bare short circuit of the battery, caused by accidental contact of the outer terminal of the battery holder to the ground through the housing and the shield of the mini-USB inlet. It's recommended to use some insulation material such as Kapton(R) tapes between the battery holder and the housing.
Note *2 : The housing of the calculator is not electrically connected to the PCB. It's recommended to connect the housing to the ground of the PCB to prevent ESD and EMI problems.
Note *3 : It seems to correct dust easily by electro-static because both the keypad overlay and the paint of the housing are not treated nor made of anti-static materials. To make the things worse, its physical shape work as a scraper to gather the dust into the calculator through the large clearance between the housing and its front pannel. It's recommended to use anti-static materials for the calculator body, and preferably to use dust seal or at least dust preventing structures.

Current draw

Power off state (sleep) current I_sleep ≤ 1.8uA (Vdd = 3.00V, Ta = 25C)

Test circuit (DUT = DM-15CC, firmware = DM15CC_MEM1B_V10)

Note *4 : Vdd of 3.00V is shown as 2.815V in the information displayed by [ON]+[E]

Standby current (Vdd = 3.00V, Ta = 25C)

mode = 12MHz ( 5mV/div ≡ 1mA/div) mode = 48MHz ( 5mV/div ≡ 1mA/div)

Note *5 : There seems to be a problem in standby state of 12MHz mode. Its average standby current is much higher than that of 48MHz mode.
Operating current ^*6(Vdd = 3.00V, Ta = 25C)

mode = 12MHz ( 5mV/div ≡ 1mA/div) mode = 48MHz (20mV/div ≡ 4mA/div)

Note *6 : while executing self test invoked by pressing [ON] and [×].

Key combinations

keys function description
[ON]+[B] benchmark evaluate benchmark compared with orig. calc
[ON]+[C] serial console switch to serial console (38400, 8N1, without flow control)
[ON]+[E] show information firmware version & battery voltage
[ON]+[CHS] LCD settings change LCD contrast
[ON]+[7] change font toggle from 7segment to smooth font and back again
[ON]+[9] change speed toggle from 12MHz to 48MHz and back again
[ON]+[/] key test same as on the original calculator
[ON]+[*] self test same as on the original calculator
[ON]+[-] power reset same as on the original calculator
[ON]+[+] same as on the original calculator
[ON]+[.] toggle . and , same as on the original calculator

Serial console (38400bps, 8bit, parity none, 1 stop bit, no flow control)

serial console command help
`VOYAGER >> ? Firmware DM15CC_MEM1B_V10 ? Help p Key press s Dump memory l Load memory t Toggle display output to console b Read battery voltage Type '<command> ?' for params Uptime 72s VOYAGER >>`

Benchmark result

N-queen benchmark : 3m16s (DM15CC MEM1B V9 48MHz), x = 876, y = 8

Memory dump (calculator model = DM15CC_MEM1B V14)

example1 - N-queen benchmark

example2 - Electrical Engineering library
Programs in the Engineering library
Entry
point function input output

A Synthesize
Microstripline

Z→w X = Z_microstrip
R₇ = ε_r
R₈ = height
R₉ = thickness X = width

Y = 1/√ε_{r_eff}

B Analyze
Microstripline

w→Z X = width
R₇ = ε_r
R₈ = height
R₉ = thickness X = Z_microstrip
Y = 1/√ε_{r_eff}

C Rational
interpolation X = x_i
R₁ = x₁, R₂ = x₂, R₃ = x₃
R₄ = y₁, R₅ = y₂, R₆ = y₃ X = y_i

D Differential
Impedance
s→Z_diff X = side gap
R₀ = Z
R₈ = height X = Z_diff

E factor X = positive integer E = factors

1 Z→S₁₁ X = R + jX X = S₁₁
Y = Return loss
Z = VSWR

2 LCM
GCD X = positive integer
Y = positive integer X = LCM
Y = GCD

3 Fractional
approximation X = decimal number X = denominator
Y = numerator

Programs in the Engineering library
Entry point	function	input	output
A	Synthesize Microstripline Z→w	X = Z_microstrip R₇ = ε_r R₈ = height R₉ = thickness	X = width Y = 1/√ε_{r_eff}
B	Analyze Microstripline w→Z	X = width R₇ = ε_r R₈ = height R₉ = thickness	X = Z_microstrip Y = 1/√ε_{r_eff}
C	Rational interpolation	X = x_i R₁ = x₁, R₂ = x₂, R₃ = x₃ R₄ = y₁, R₅ = y₂, R₆ = y₃	X = y_i
D	Differential Impedance s→Z_diff	X = side gap R₀ = Z R₈ = height	X = Z_diff
E	factor	X = positive integer	E = factors
1	Z→S₁₁	X = R + jX	X = S₁₁ Y = Return loss Z = VSWR
2	LCM GCD	X = positive integer Y = positive integer	X = LCM Y = GCD
3	Fractional approximation	X = decimal number	X = denominator Y = numerator

APPENDIX - Program library

Factr - Factor a positive integer
Frac - Fractional approximation
LCM/GCD - LCM and GCD of two positive integers
LCR - Resonant frequency of a LC resonator
μZw, μwZ - Synthesize/Analyze microstrip transmissionline
RI - Rational interpolation
Z→S - Impedance Z to S₁₁ scattering parameter conversion

EXTERNAL LINKS

DM swiss made calculators
The Museum of HP Calculators
Flash Magic Tool
Silicon labs, CP210x USB to UART Bridge VCP Drivers

Smooth font Firmware = DM15CC_MEM80_V8	Slim font Firmware = DM15CC_S_V10

mode = 12MHz ( 5mV/div ≡ 1mA/div)	mode = 48MHz ( 5mV/div ≡ 1mA/div)

mode = 12MHz ( 5mV/div ≡ 1mA/div)	mode = 48MHz (20mV/div ≡ 4mA/div)

keys	function	description
[ON]+[B]	benchmark	evaluate benchmark compared with orig. calc
[ON]+[C]	serial console	switch to serial console (38400, 8N1, without flow control)
[ON]+[E]	show information	firmware version & battery voltage
[ON]+[CHS]	LCD settings	change LCD contrast
[ON]+[7]	change font	toggle from 7segment to smooth font and back again
[ON]+[9]	change speed	toggle from 12MHz to 48MHz and back again
[ON]+[/]	key test	same as on the original calculator
[ON]+[*]	self test	same as on the original calculator
[ON]+[-]	power reset	same as on the original calculator
[ON]+[+]		same as on the original calculator
[ON]+[.]	toggle . and ,	same as on the original calculator

Front view and its font

Internal view

Current draw

Key combinations

Serial console (38400bps, 8bit, parity none, 1 stop bit, no flow control)

Benchmark result

Memory dump (calculator model = DM15CC_MEM1B V14)

APPENDIX - Program library

SEE ALSO

EXTERNAL LINKS