Board XH M194
The board is advertised as "5-way" although it has 6 relay channels, and there is no obvious reason why it shouldn't be called a "6-way Relay" module. It's also not a "Value Line Gadget" since it's powered by an Access Line device (16-32K Flash, 2K RAM).
The XH-M194 board has the following characteristics:
- STM8S105S4T6, SWIM interface on 4 pin header (pins unpopulated)
- 5.0V internal supply voltage
- DS1302 RTC
Unfortunately the design of the board is unimaginative: I2C pins are N/C, the UART wasted for clocking the LED shit register, the SSC for controlling LEDs and the analog inputs used for keys (both could have been multiplexed). As many as 5 GPIOs are were left N/C and not a single one of them was made available on a pin header. It's clear to see that at now extra cost the XH M194 board could have been a RS485 node, a RF connected device, a development board... but as it is now it's just an overpowered clock with relays.
The following features are supported:
- Half-duplex serial console pin PD1/SWIM
- LED display (serial console has priority over colon dots)
- DS1302 clock (register and RAM access), time decoding
- 6 relays and 6 green LEDs controlled by
OUT! - 6 keys mapped through
BKEYand?KEYB
There are no analog or digital inputs - the hardware has to be modified to obtain some (e.g. remove green LEDs and re-purpose GPIOs).
The board support code provides basic register access. Please refer to XH-M192/board.fs.
The word OUT! puts a binary pattern to the outputs. The outputs are assigned as follows:
| OUT bit value | Relay | OUT bit value | Green LED |
|---|---|---|---|
| 0x01 | relay 1 | 0x0100 | LED 1 |
| 0x02 | relay 2 | 0x0200 | LED 2 |
| 0x04 | relay 3 | 0x0400 | LED 3 |
| 0x08 | relay 4 | 0x0800 | LED 4 |
| 0x10 | relay 5 | 0x1000 | LED 5 |
| 0x20 | relay 6 | 0x2000 | LED 6 |
The 6 keys are mapped as follows:
| Key | ?KEYB | BKEY |
|---|---|---|
| "R" | "A" (0x41) | 0x01 |
| "L" | "B" (0x42) | 0x02 |
| ">" | "D" (0x44) | 0x04 |
| "v" | "H" (0x48) | 0x08 |
| "^" | "P" (0x56) | 0x10 |
| "<" | "`" (0x96) | 0x20 |
Pressing multiple keys leads to an ASCII code corresponding to the value of the bit-field (e.g. "R" and ">" result in the code 0x45 (ASCII "E").
A decimal point after the 2nd digit controls the colon dots:
: test ." AB.CD" ;
' test BG !
After a 30s "blackout period" this will be rendered on the LED display as Ab:Cd.
The board support provides half-duplex console access through PD1/SWIM on the ICP header. Please note that PD1 also controls the 7S-LED colon segment. Up to 30 seconds after a serial transmissions, the LED display is blanked to improve robustness of the communication.
The half-duplex interface is designed to work with e4thcom, or with the example Picocom configuration for half-duplex communication described here.
The following sketch shows how to connect a serial interface adapter using the SWIMCOM method:
................
XH-M194 .
. .----o serial TxD "TTL"
( ) . | e.g. "PL2302 USB serial converter"
. ---
. / \ 1N4148
VCC ------<1> . ---
. |
PD1/SWIM--<2>--.------*----o serial RxD "TTL"
.
NRST------<3> .
.
GND-------[4]--.-----------o serial GND
.
ICP header .
The STM8S105S4 pins are connected as follows:
Pin STM Connected to
-------------------------------------
1 NRST
2 PA1 LED green R3
3 PA2 LED green R4
4 VSSIO_1 I/O ground
5 VSS digital ground
6 VCAP
7 VDD digital power supply
8 VDDIO_1 I/O power supply
9 PA4 LED green R5
10 PA5 LED green R6
11 PA6 DS1302 pin 7 SCLK
12 VDDA analog power supply
13 VSSA analog ground
14 PB7/AIN7 DS1302 pin 6 I/O
15 PB6/AIN6 DS1302 pin 5 CE
16 PB5/AIN5 key <
17 PB4/AIN4 key ^
18 PB3/AIN3 key v
19 PB2/AIN2 key >
20 PB1/AIN1 key L (leftmost)
21 PB0/AIN0 key R (rightmost)
22 PE6/AIN9 n/c
23 PE5 LED green R2
24 PC1 LED green R1
25 PC2 LED red R6
26 PC3 LED red R5
27 PC5 LED red R3
28 VSSIO_2 I/O ground
29 VDDIO_2 I/O power supply
30 PC6 LED red R2
31 PC7 LED red R1
32 PG0 LED red R4
33 PG1 n/c
34 PE2 n/c (I2C_SDA)
35 PE1 n/c (I2C_SCL)
36 PE0 n/c
37 PD0 7S-digit4 (rightmost)
38 PD1 SWIM 7S-COLON
39 PD2 7S-digit3
40 PD3 7S-digit2
41 PD4 7S-digit1 (leftmost)
42 PD5 74HC595-14-DS s-in UART2_RX
43 PD6 74HC595-11-SHCP sclk UART2_TX
44 PD7 74HC595-12-STCP pclk TLI
74HC595
Symbol Pin Description
-------------------------------------
Q1 1 7S-B
Q2 2 7S-C
Q3 3 7S-D
Q4 4 7S-E
Q5 5 7S-F
Q6 6 7S-G
Q7 7 n/c
GND 8 ground (0 V)
Q7S 9 serial data output
MR 10 (VCC) master reset (active LOW)
SHCP 11 43 pull-up / shift register clock input
STCP 12 44 pull-up / storage register clock input
OE 13 GND / output enable input (active LOW)
DS 14 42 pull-up / serial data input
Q0 15 7S-A
VCC 16 supply voltage
DS1302 Trickle-Charge Timekeeping Chip
Symbol Pin Description
-------------------------------------
VCC2 1
X1 2 xtal out
X2 3 xtal in
GND 4
CE 5 * 15 PB6 / chip enable
I/O 6 * 14 PB7 / serial in/out
SCLK 7 * 11 PA6 / clock in
VCC1 8 (rechargeable) battery
7S-LED Clock Display
The display on the board examined resembles closely the one in the following picture:
However, there doesn't appear to be a real standard for 12pin clock display: there are variants with colon dots multiplexed with digit1, digit2, and digit3+digit4, and only rarely some DP segments are provided (14pin clock displays provide DP segments and non-multiplexed colon dots).
The board support code exports CFGDOTS as a configuration point for the multiplex type.
Refer to issue #128.