VMAC PiHat v2 OSD
The HAMKit VMAC PiHat features an on-board, tried and trusted, MAX7456 single-channel monochrome on-screen display (OSD) generator.
The MAX7456 serves all national and international markets with 256 user-programmable characters in both NTSC and PAL standards. The MAX7456 easily displays information such as company logo, custom graphics, time, and date with arbitrary characters and sizes. The MAX7456 is preloaded with 256 characters and pictographs and can be reprogrammed in-circuit using the SPI port.
Using the HAMKit VMAC PiHat video matrix, we are able to take any input to the matrix, map this into the OSD, then take the OSD video output and map to any matrix video output.
Key OSD Features
- 256 User-Defined Characters or Pictographs in Integrated EEPROM
- 12 x 18 Pixel Character Size
- Blinking, Inverse, and Background Control Character Attributes
- Selectable Brightness by Row
- Displays Up to 16 Rows x 30 Characters (PAL)
- Sag Compensation On Video-Driver Output
- LOS, Active-Low VSYNC, Active-Low HSYNC, and Clock Outputs
- Internal Sync Generator
- NTSC and PAL Compatible
- SPI-Compatible Serial Interface
- Preprogrammed Character Set
In the below test code
- Video Input 1, is mapped to the OSD input. The OSD output is then mapped to Video Out 1
- Video Input 1, is mapped to the Video Out 2 as a straight thru clean video test
- The OSD IC is enabled and setup to display a basic test page
- Any video on input 1 will get super-imposed OSD text and displayed on output 1. With no OSD on output 2
Example output from the below test code
# Example of matrix mapping # Video 1 Input to OSD Input 0x07 0x81 # OSD Output to Video 1 Output 0x01 0x86 ... i2cbus.write_byte_data(DEVICE_ADDR, 0x07, 0x81) #Input 1 to OSD In i2cbus.write_byte_data(DEVICE_ADDR, 0x01, 0x86) #Input OSD to Output 1
All of our sample and test code is developed in Python.
# HAMKit VMAC PiHat v2.3 - Test OSD - Dave Williams G8PUO
# Setup matrix input and outputs, enable OSD and display a test page
# Video 1 Input to OSD Input 0x07 0x81
# OSD Output to Video 1 Output 0x01 0x86
# Video 1 Input to Video 2 Output 0x03 0x81 (Thru Video Test)
# July 2018. Thanks to Paul Theunissen, PA5PT, for OSD code template
#!/usr/bin/python
import smbus
import RPi.GPIO as GPIO
import spidev
import time
from ctypes import *
#====== GPIO
GPIO.setmode(GPIO.BCM)
GPIO.setwarnings(False)
#GPIO.cleanup()
#Define GPIO Outputs
LEDStatus = 22
PTT = 27
OSD_RST = 25
#Setup Outputs
GPIO.setup(LEDStatus,GPIO.OUT)
GPIO.setup(PTT,GPIO.OUT)
GPIO.setup(OSD_RST,GPIO.OUT)
#Initiate LEDs
GPIO.output(LEDStatus,GPIO.HIGH)
GPIO.output(PTT,GPIO.HIGH)
time.sleep(0.5)
GPIO.output(LEDStatus,GPIO.LOW)
GPIO.output(PTT,GPIO.LOW)
time.sleep(0.5)
#====== FMS6501 Matrix
#define values
DEVICE_BUS = 1
DEVICE_ADDR = 0x43 #0x43 or 0x03
#setup i2c bus
i2cbus = smbus.SMBus(DEVICE_BUS)
#OSD REset High
GPIO.output(OSD_RST,GPIO.HIGH)
def PowerDownPorts():
print ("PowerDownPorts")
i2cbus.write_byte_data(DEVICE_ADDR, 0x01, 0x0) #Mute
time.sleep(.01)
i2cbus.write_byte_data(DEVICE_ADDR, 0x03, 0x0) #Mute
time.sleep(.01)
i2cbus.write_byte_data(DEVICE_ADDR, 0x06, 0x0) #Mute
time.sleep(.01)
i2cbus.write_byte_data(DEVICE_ADDR, 0x07, 0x0) #Mute
time.sleep(.01)
i2cbus.write_byte_data(DEVICE_ADDR, 0x08, 0x0) #Mute
time.sleep(.01)
i2cbus.write_byte_data(DEVICE_ADDR, 0x09, 0x0) #Mute
time.sleep(.01)
#Disable and Powerdown Matrix Outputs
PowerDownPorts()
# Setup Matrix Video Switching
i2cbus.write_byte_data(DEVICE_ADDR, 0x1d, 0xff) #clamp
i2cbus.write_byte_data(DEVICE_ADDR, 0x1e, 0xff) #clamp
i2cbus.write_byte_data(DEVICE_ADDR, 0x07, 0x81) #Input 1 to OSD In
i2cbus.write_byte_data(DEVICE_ADDR, 0x01, 0x86) #Input OSD to Output 1
i2cbus.write_byte_data(DEVICE_ADDR, 0x03, 0x81) #Input 1 to Output 2
#OSD MAX7456
class max7456():
# Create a SPI
spi = spidev.SpiDev()
# MAX7456 opcodes
VM0_reg = 0x00
VM1_reg = 0x01
HOS_reg = 0x02
VOS_reg = 0x03
DMM_reg = 0x04
DMAH = 0x05
DMAL = 0x06
DMDI = 0x07
OSDM = 0x0C
RB0 = 0x10
HOS_reg = 0x02
STATUS = 0xA0
# PAL - VM0_reg commands
ENABLE_display = 0x48
ENABLE_display_vert = 0x4c
MAX7456_reset = 0x42
DISABLE_display = 0x40
# Read command
READ = 0x80
MAX_screen_rows = 16
# White levels
WHITE_level_80 = 0x03
WHITE_level_90 = 0x02
WHITE_level_100 = 0x01
WHITE_level_120 = 0x00
chars = {' ':0, '1':1, '2':2, '3':3, '4':4, '5':5, '6':6, '7':7, '8':8, '9':9,
'0':10, 'A':11, 'B':12, 'C':13, 'D':14, 'E':15, 'F':16, 'G':17, 'H':18, 'I':19,
'J':20, 'K':21, 'L':22, 'M':23, 'N':24, 'O':25, 'P':26, 'Q':27, 'R':28, 'S':29,
'T':30, 'U':31, 'V':32, 'W':33, 'X':34, 'Y':35, 'Z':36, 'a':37, 'b':38, 'c':39,
'd':40, 'e':41, 'f':42, 'g':43, 'h':44, 'i':45, 'j':46, 'k':47, 'l':48, 'm':49,
'n':50, 'o':51, 'p':52, 'q':53, 'r':54, 's':55, 't':56, 'u':57, 'v':58, 'x':59,
'y':60, 'z':61, '(':62, ')':63, '.':64, '?':65, ';':66, ':':67, ',':68, '\'':69,
'/':70, '"':71, '-':72, '<':73, '>':74, '@':75, '\xa9':76
}
def __init__(self):
# Open a SPI port - max7456 connected on SPI0
self.spi.open(0, 0)
self.spi.max_speed_hz = 1000000
self.spi.bits_per_word = 8
self.spi.cshigh = False
self.spi.lsbfirst = False
self.spi.mode = 0
# On init, reset max7456
self.reset()
# Set all rows at the same white level
for x in range (0, self.MAX_screen_rows):
self.spi.xfer2([(self.RB0 + x), self.WHITE_level_90])
# Enable max7456
self.spi.xfer2([self.VM0_reg, self.ENABLE_display]);
def printStr(self, X, Y, string, enable = True):
disp = []
for char in string:
disp.append(self.chars[char])
print (string)
if enable == False:
self.spi.xfer([self.VM0_reg, self.Disable_display])
# Enable 8 bit mode:
dmm = self.spi.xfer2([self.DMM_reg + self.READ, 0x00])
dmm = self.setBit(dmm[1], 6)
self.spi.xfer2([self.DMM_reg, dmm])
start = X * 30 + Y
# Clear position
self.spi.xfer2([self.DMAH, 0x00])
self.spi.xfer2([self.DMAL, 0x00])
for char in disp:
# Write char
dmah = self.spi.xfer2([self.DMAH + self.READ, 0x00])
dmah = self.clearBit(dmah[1], 1)
self.spi.xfer2([self.DMAH, dmah])
dmah_pos = ((start >> 8) & 0x01)
dmal = (start & 0xff)
dmah = dmah | dmah_pos
start = start + 1
# Select MSB
self.spi.xfer2([self.DMAH, dmah])
self.spi.xfer2([self.DMAL, dmal])
self.spi.xfer2([self.DMDI, (char)])
def reset(self):
self.spi.xfer2([self.VM0_reg, self.MAX7456_reset])
time.sleep(0.1)
while True:
r = self.spi.xfer([self.STATUS, 0x00])
stable = self.testBit(r[1], 1)
if stable == 0:
print ("Reset MAX7456 Ok...")
break
break
def testBit(self, value, offset):
mask = 1 << value
return(value & mask)
def setBit(self, value, offset):
mask = 1 << offset
return(value + mask)
def clearBit(self, int_type, offset):
mask = ~(1 << offset)
return(int_type & mask)
try:
max7456 = max7456()
#Display OSD Text
max7456.printStr(2,5, "VMAC Tesing 1 2 3 4", enable = True)
max7456.printStr(5,5, "OSD Test ABCDEFGHIJ", enable = True)
max7456.printStr(9,1, "1234567890123456789012345678", enable = True)
max7456.printStr(13,5, "HAMKit VMAC PiHat v2", enable = True)
except KeyboardInterrupt:
spi.close()
Further details on the configuration and test code can be found in other Wiki pages. Also see programming and developing in Python.