def num_devices(self):
"""return the number of JTAG devices in the chain"""
# put every device into bypass mode (IR = all 1's)
self.driver.scan_ir(bits.ones(_flush_size))
# now each DR is a single bit
# the DR chain length is the number of devices
return self.dr_length()
def test_ir_capture(self):
"""test the IR capture result"""
# write all-1s to the IR
rd = self.rw_ir(bits.ones(self.irlen))
val = rd.split((self.irlen, ))[0]
# the lowest 2 bits should be "01"
return val & 3 == 1
def read_idcodes(self):
"""return a tuple of idcodes for the JTAG chain"""
# a TAP reset leaves the idcodes in the DR chain
self.driver.tap_reset()
tdi = bits.ones(self.n * _idcode_length)
tdo = bits.null()
self.driver.scan_dr(tdi, tdo)
return tdo.split((_idcode_length, ) * self.n)
def rw_dr(self, wr):
"""read/write DR for a device"""
tdi = bits.ones(self.devs_before).tail(wr).tail1(self.devs_after)
tdo = bits.null()
self.chain.driver.scan_dr(tdi, tdo)
# strip the dr bits from the bypassed devices
tdo.drop_head(self.devs_before)
tdo.drop_tail(self.devs_after)
return tdo
def rw_ir(self, wr):
"""read/write IR for a device"""
tdi = bits.ones(self.irlen_before).tail(wr).tail1(self.irlen_after)
tdo = bits.null()
self.chain.driver.scan_ir(tdi, tdo)
# strip the ir bits from the other devices
tdo.drop_head(self.irlen_before)
tdo.drop_tail(self.irlen_after)
return tdo
def test5(self):
x = bits.ones(7).tail0(4)
self.assertEqual(str(x), '(11) 00001111111')
def test2(self):
x = bits.ones(3)
self.assertEqual(str(x), '(3) 111')
def wr_dr(self, wr):
"""write to DR for a device"""
# other devices are assumed to be in bypass mode (dr length = 1)
tdi = bits.ones(self.devs_before).tail(wr).tail1(self.devs_after)
self.chain.driver.scan_dr(tdi)
def wr_ir(self, wr):
"""write to IR for a device"""
# place other devices into bypass mode (ir = all 1's)
tdi = bits.ones(self.irlen_before).tail(wr).tail1(self.irlen_after)
self.chain.driver.scan_ir(tdi)
